1. Current Diagnosis and Mechanisms of Glucose Dysregulation
Dr. Josephine Carlos-Raboca
Chief, Section of Endocrinology, Diabetes & Metabolism
Makati Medical Center
Immediate Past President, PSEM

2. Outline Overview of glucose regulation
Stages of Dysglycemia (glucose dysregulation)
Current Diagnostic Criteria for dysglycemia
Mechanisms of Glucose Dysregulation
Summary

3. Glucose Metabolism
Tightly regulated to maintain adequate plasma levels
Major hormones
insulin
glucagon
incretins
Major organs
islet cells of pancreas
insulin sensitive organs: liver, muscle, fat
intestines
Kidneys
Modulator
Endocannabinoid System

4. Role of Pancreatic Islets in Normal Glucose Homeostasis
Islet as an Organ:
Role of Pancreatic Islets in Normal
Glucose Homeostasis

5. Islet of Langerhans ~ 3,000 cells 75% Beta cells 200 µm
25% non-Beta cells
200 µm
Micrograph: Lelio Orci, Geneva

6. Beta and Alpha Cells in the Pancreas of Normal Individuals
Beta Cells
Alpha Cells
Comprise about 50% of the endocrine mass of the pancreas1
Comprise about 35% of the endocrine mass of the pancreas1
Produce insulin and amylin2
Produce glucagon2
Insulin released in response to elevated blood glucose levels2
Glucagon released in response to low blood glucose levels2 leading to increase in glucose
Slide 3
Beta and Alpha Cells in the Pancreas of Normal Individuals
Pancreatic islets of Langerhans occupy approximately 1% to 5% of the total pancreatic mass in human adults. They are randomly distributed throughout the exocrine pancreas but their density is slightly greater in the pancreatic head. Located within the pancreatic islets are endocrine cells known as pancreatic beta and alpha cells.1
Beta cells, which comprise about 50% of the endocrine mass of the pancreas, are located in the central portion of the islet.2,3 Beta cells produce insulin, which is released in response to elevated blood glucose levels.3,4 The hormone IAPP (also known as amylin) is also produced by beta cells.5 Patients with type 2 diabetes exhibit some deficit in IAPP production.5
Alpha cells, which comprise about 35% of the endocrine mass of the pancreas, are located in the periphery of the islets.2 Alpha cells produce glucagon, which is released in response to low blood glucose levels.4
Glucose homeostasis requires the integrated functioning of beta and alpha cells.6
1. Cabrera O et al. PNAS. 2006;103:2334–2339.
2. Cleaver O et al. In: Joslin’s Diabetes Mellitus. Lippincott Williams & Wilkins; 2005:21–39.
References:
1. Foulis AK, Clark A. Pathology of the pancreas in diabetes mellitus. In: Kahn CR, Weir GC, eds. Joslin’s Diabetes Mellitus. 13th ed. Philadelphia, Pa: Lea & Febiger; 1994:265–281.
2. Cabrera O, Berman DM, Kenyon N, et al. The unique cytoarchitecture of human pancreatic islets has implications for islet function. PNAS. 2006;103:2334–2339.
3. Rhodes CJ. Type 2 diabetes—a matter of beta-cell life and death? Science. 2005;307:380–384.
4. Cleaver O, Melton DA. Development of the endocrine pancreas. In: Kahn CR, Weir OC, King GL, Jacobson AM, Moses AC, Smith RJ, eds. Joslin’s Diabetes Mellitus. 14th ed. Philadelphia, Pa: Lippincott Williams & Wilkins; 2005:21–39.
5. Kahn SE, Verchere CB, Andrikopoulos S, et al. Reduced amylin release is a characteristic of impaired glucose tolerance and type 2 diabetes in Japanese Americans. Diabetes. 1998;47:640–645.
6. Porte D Jr, Kahn SE. The key role of islet dysfunction in type II diabetes mellitus. Clin Invest Med. 1995;18:247–254.

7. Insulin Production Primary regulators for insulin biosynthesis glucose
glucagon
incretins- GLP-1, GIP
Inhibits insulin biosynthesis
catecholamine
somatostatin

8. Glucagon Main regulator- glucose amino acids incretins Insulin
fatty acids
ketones

9. Insulin and Glucagon Regulate Normal Glucose Homeostasis
(Alpha cell)
(–)
(–)
Pancreas
(+)
Slide 4
(+)
Insulin and Glucagon Regulate Normal Glucose Homeostasis
Normal glucose homeostasis is maintained through a feedback relationship between insulin, glucagon, and circulating glucose.1
In times of low glucose intake (fasting state, between meals, after an overnight fast, or in cases of starvation) when glucose levels are falling, the alpha cells of the pancreas release glucagon.1,2
Glucagon directs the liver to break down stored glycogen into glucose and to release this glucose into the bloodstream, thereby raising blood glucose concentration to a desired level. Thus, there is an increase in glucose production.
There is also a decrease in insulin secretion by the beta cells.1
In the fed state, glucose enters the bloodstream and a rise in glucose level is detected by the specialized beta cells in the pancreas. Beta cells respond to the rising blood glucose concentration by promptly releasing insulin.1
Insulin signals to other tissues in the body to take in glucose to be used as energy or stored for later use.1
Insulin also signals the liver to turn off glucose production.1
The net result is the lowering of blood glucose concentration.
In the fed state, glucagon is suppressed. The suppression of glucagon contributes to a decrease in glucose production.1
Insulin
(Beta cell)
(–)
(+)
Glucose output
Glucose uptake
Liver
Blood glucose
Muscle and adipose tissue
Porte D Jr et al. Clin Invest Med. 1995;18:247–254.
Adapted from Kahn CR, Saltiel AR. Joslin’s Diabetes Mellitus. 14th ed. Lippincott Williams & Wilkins; 2005:145–168.
References:
1. Porte D Jr, Kahn SE. The key role of islet dysfunction in type II diabetes mellitus. Clin Invest Med ;18:247–254.
2. Unger RH. Glucagon and the insulin:glucagon ratio in diabetes and other catabolic illnesses. Diabetes. 1971;20:834–838.

10. GUT and GUT Hormones
Na ATP channels – absorption of glucose
Incretins

11. Incretins Regulate Glucose Homeostasis Through Effects on Islet-Cell Function
1/Brubaker, p 2653, C1, ¶2, L1-6, C2, L3-7
2/Zander 2002,
p 828, C2, ¶2, L10-14;
p 829, C1, ¶2, L1-6,
C2, L1, 10-12, 15-23
3/Ahrén,
p 366, C2, ¶3, L1-3,8-9;
p 370, C1, ¶2, L1-4
5/Buse,
p 1441, C2, ¶2, L1-7, ¶3, L1-7
CMK
Ingestion of food
 Insulin in glucose-dependent way
from β cells (GLP-1 and GIP)
Increased peripheral glucose uptake
Release of incretin gut hormones
The presence of nutrients in the gastrointestinal tract rapidly stimulates the release of incretins: GLP-1 from L cells located primarily in the distal gut (ileum and colon), and GIP from K cells in the proximal gut (duodenum).1,2
Collectively, these incretins exert several beneficial actions, including stimulating the insulin response in pancreatic beta cells and reducing glucagon production from pancreatic alpha cells when glucose levels are elevated.3,4 Increased insulin levels improve glucose uptake by peripheral tissues; the combination of increased insulin and decreased glucagon reduces hepatic glucose output.5
GI tract
Pancreas
 INSULIN
1/Brubaker, p 2653, C1, ¶2, L1-6, C2, L3-7
2/Zander 2002,
p 828, C2, ¶2, L10-14; p 829,
C1, ¶2, L1-6,
C2,L1,10-12, 15-23
3/Ahrén, p 366, C2, ¶3, L1-3,8-9; p 370,
C1, ¶2, L1-4
4/Drucker 2002,
p 535, C1, ¶1, L1-7
5/Buse,
p 1441, C2, ¶2, L1-7, ¶3, L1-7
β cells
Blood glucose control
 Blood glucose control
α cells
Active GLP-1 and GIP
↓ GLUCAGON
Decreased hepatic glucose output
 Glucagon
in glucose- dependent way from α cells (GLP-1)
Inactive GLP-1 (9-36)
and GIP (3-42)
Slide has been approved by M/L. Slide #11 in Phase II Kit
Adapted from Brubaker PL, Drucker DJ. Endocrinology. 2004;145: ;Zander M et al. Lancet. 2002;359: ; Ahrén B. Curr Diab Rep. 2003;3: ; Buse JB et al. In Larsen PR et al, eds.: Williams Textbook of Endocrinology. 10th ed. Philadelphia, PA: Saunders; 2003:
References:
1. Brubaker PL, Drucker DJ. Minireview: Glucagon-like peptides regulate cell proliferation and apoptosis in the pancreas, gut, and central nervous system. Endocrinology 2004;145: 2653–2659.
2. Zander M, Madsbad S, Madsen JL et al. Effect of 6-week course of glucagon-like peptide 1 on glycaemic control, insulin sensitivity, and -cell function in type 2 diabetes: A parallel-group study. Lancet 2002;359:824–830.
3. Ahrén B. Gut peptides and type 2 diabetes mellitus treatment. Curr Diab Rep 2003;3:365–372.
4. Drucker DJ. Biological actions and therapeutic potential of the glucagon-like peptides. Gastroenterology 2002;122:531–544.
5. Buse JB, Polonsky KS, Burant CF. Type 2 diabetes mellitus. In: Larsen PR, Kronenberg HM, Melmed S et al, eds. Williams Textbook of Endocrinology. 10th ed. Philadelphia: Saunders, 2003:1427–1483. 11

13. The endocannabinoid system is a modulatory system
Synthesized on demand from lipid precursors in postsynaptic cell
CB1 receptors:
Play a key role in energy balance and lipid and glucose metabolism
The endocannabinoid system (ECS) is modulatory in nature, affecting the actions of other systems. Endocannabinoids are derived from lipid precursors and are activated locally ‘on demand’ (not stored in vesicles) with synthesis occurring in postsynaptic cells.
The activation of CB1 receptors occurs presynaptically.
Unlike most neurotransmitters, endocannabinoids are often synthesized in the postsynaptic neuron and then travel backwards across synapses in a process called retrograde signaling. They activate CB1 receptors on presynaptic axons and inhibit release of other neurotransmitters.
CB1 receptors play a key role in energy balance, and are directly implicated in lipid and glucose metabolism.
Di Marzo V et al, 2005; Di Marzo V et al, 1998;
Wilson R et al, 2002
Di Marzo V, Matias I. Endocannabinoid control of food intake and energy balance. Nature Neurosci 2005;8: 585–589.
Di Marzo V, Melck D, Bisogno T, De Petrocellis L. Endocannabinoids: endogenous cannabinoid receptor ligands with neuromodulatory action. Trends Neurosci 1998;21:521–528.
Wilson RI, Nicholl RA. Endocannabinoid signaling in the brain. Science 2002;296:678–682.

14. Central and peripheral targets of the endocannabinoid system
Adipose
tissue
Muscle
Liver
GI tract
Increased food intake
Increased fat storage
Insulin resistance
HDL-cholesterol
Triglycerides
Glucose uptake
Adiponectin
Hypothalamus:
hunger
Nucleus accumbens:
motivation to eat ^
Brain
Peripheral tissues
CB1 receptors have been shown to play an important role in energy balance and are directly implicated in lipid and glucose metabolism. CB1 receptors are located centrally in the brain, and peripherally in adipose tissue, liver, skeletal muscle and the gastrointestinal tract.
In the brain, the hypothalamus plays a principal role in the control of feeding and regulation of body weight, and CB1 receptor stimulation leads to dopamine release in the nucleus accumbens shell, which increases motivation to eat. These effects result in increased food intake and fat accumulation.
Peripherally, the ECS promotes lipogenesis at the level of adipose tissue and the liver. ECS activity in the gastrointestinal tract interferes with feelings of satiety, and CB1 receptor stimulation of skeletal muscle decreases glucose uptake. All of these central and peripheral effects indicate that an overactivated ECS could contribute to the increased risk of atherogenic dyslipidaemia (low HDL-cholesterol, high triglycerides), insulin resistance, glucose intolerance and increased cardiometabolic risk.
HDL: high-density lipoprotein
Bensaid M et al, 2003; Pagotto U et al, 2005;
Osei-Hyiaman D et al, 2005;
Di Marzo V et al, 2005; Liu YL et al, 2005
Bensaid M, Gary-Bobo M, Esclangon A, et al. The cannabinoid CB1 receptor antagonist SR increases Acrp30 mRNA expression in adipose tissue of obese fa/fa rats and in cultured adipocyte cells. Mol Pharmacol 2003;63:908–14.
Pagotto U, Vicennati V, Pasquali R. The endocannabinoid system and the treatment of obesity. Ann Med 2005;37:270–275.
Osei-Hyiaman D, DePetrillo M, Pacher P, et al. Endocannabinoid activation at hepatic CB1 receptors stimulates fatty acid synthesis and contributes to diet-induced obesity. J Clin Invest 2005;115:1298–1305.
Di Marzo V, Matias I. Endocannabinoid control of food intake and energy balance. Nature Neurosci 2005;8:585–589.
Liu YL, Connoley IP, Wilson CA, Stock MJ. Effects of the cannabinoid CB1 receptor antagonist SR on oxygen consumption and soleus muscle glucose uptake in Lep(ob)/Lep(ob) mice. Int J Obes Relat Metab Disord 2005;29:183–187.

15. Regulation of glucose Homeostasis
Na dependent transporters in proximal tubules of kidneys cotransport glucose with sodium maintained by Na+/K+-ATPase ion pump

16. Glucose homeostasis
Is a balance of glucose appearance and disappearance
Glucose appearance:
endogenous glucose production (liver, muscle and kidneys)
exogenous sources (GIT) affected by feeding signals
Glucose disappearance
peripheral uptake from liver, muscle and fat

17. Prediabetes and Diabetes
Current Diagnosis of
Prediabetes and Diabetes

18. Definition of Diabetes
A metabolic dysregulation
Hallmark: hyperglycemia
Basic defects:
Islet cell dysfunction
Insulin insensitivity
Impaired action of insulin on target tissues
Diagnosis requires a cutpoint to discriminate normal from diabetic. Diabetes (also known as diabetes mellitus) has several forms, but each is characterized by excessively high blood glucose (hyperglycaemia). The hyperglycaemia is caused by either defects in insulin production or insensitivity to insulin, or both.
In type 1 diabetes, the destruction of the insulin-producing beta cells is usually an autoimmune process in people with a genetic susceptibility. The trigger for type 1 diabetes is not fully understood; many things are thought to be precursors, such as a coxsackie B4 virus or rubella.

19. Definition of Diabetes
Chronic hyperglycaemia associated with long-term damage to:
Eyes
Kidneys
Nerves
Heart and blood vessels
Over time, hyperglycaemia damages the basement cell membrane of the blood vessels, causing damage to organs – specifically the eyes, kidneys, and heart. Nerve damage (neuropathy) also occurs.

20. Hyperglycemia Stages Type Type 1 * Type 2 Other Specific Type *
Diabetes Mellitus
Impaired Glucose Tolerance or
Impaired Fasting Glucose
(Pre-Diabetes)
Normal Glucose Regulation
Type
Not insulin requiring
Insulin requiring for control
Insulin requiring for survival
Type 1 *
Type 2
Other Specific
Type *
Gestational Diabetes **

21. Diagnostic Criteria For DM
FPG
2 hours PG (after 75 g OGTT)
NORMOGLYCEMIA
< 110 mg/dL
< 140mg/dL(7.8mmol/l)
IMPAIRED FASTING GLYCEMIA (IFG)
 110 and < 126 mg/dL
---
IMPAIRED GLUCOSE TOLERANCE (IGT)
 140mg/dl(7.8mmol/l) and < 200 mg/dL(11.1mmol/l)
DIABETES MELLITUS
 126 mg/dL(7.0 mmol/l)
 200 mg/dL (11.1mmol/l)
Symptoms of diabetes and casual plasma glucose of  200 mg/dl(11.1mmol/l)
<100mg/dL (5.6mmol/l)
100mg/dl(5.6mmol)
and< 126 mg/dL(7.0)
Therefore, the need to diagnose and treat early, if not prevent diabetes is a must.
Based on the ADA
There are three ways to diagnose diabetes, and each must be confirmed on a subsequent day unless unequivocal symptoms of hyperglycemia are present.
Casual (RBS)– plasma glucose measured at any time of the day without regard to time since last meal.
Fasting – no caloric intake or no consumption of food or beverage other than water for at least 8 hours
OGTT – as described by the World Health Organization – intake of 75g anhydrous glucose dissolved in water. The test should be done in the morning after an overnight fast of at least 8 to 14 hours and after at least 3 days of unrestricted diet (>150 g carbohydrates per day) and unlimited physical activity. The subject should remain seated and should not smoke throughout the test
FPG – preferred diagnostic test because of ease of use, acceptability to patients and lower cost.
OGTT – more sensitive and modestly more specific than fasting plasma glucose to diagnose diabetes, it is poorly reproducible and rarely performed in practice.
American Diabetes Association 2003
ADA, Diabetes Care 2009

22. Hba1c
Integrated summary of circadian blood glucose in the preceding 6-8 weeks
Not used as diagnostic test for diabetes
Lack of standardized analytical method and therefore lack of a uniform non diabetic reference level between laboratories
Insensitive in the low range
Normal aic cannot exclude diabetes or IGT

23. Issues on current diagnostic cut off
3 studies on which FPG of 7.0 cutoff was based for diagnosis of diabetes used direct ophthalmoscopic examination and one retinal photograph
Diabetes Prevention Program showed substantial prevalence of retinopathy below FPG of 7.0
Cardiovascular complications occur at lower glucose levels
Definition and classification of diabetes and pre states should be based on the level of subsequent risk of cardiovascular complications class 1 level B ESC,EASD 2007
Althought FPG >7 and 2hPG >11 often don’t coincide. NHANES III 44% met both FPG and 2hPG 14% only FPG and 41% 2hPG only.

24. Relation between FPG and retinopathy
BMES AusDiab MESA
FPG
(Mean)
Number
(%) with (11.5) (9.3) (15.8) Retinopathy
Lancet 2008

25. Blue Mountains Eye Study (5-year incident retinopathy)
Any retinopathy
Percentage
Fasting plasma glucose (mmol/L)
Number with any retinopathy 40
100 24 12 3 7 2 5
Total
545
996
241 56 21 15 9
Relation between baseline FPG and incident retinopathy, BMES

26. Recommendation Current diagnostic criteria remain the best
tools for now.

27. Mechanisms of Glucose Dysregulation and Development of Type 2 Diabetes

28. Genetics
39% of patients with type 2 diabetes have at least one parent with the disease
Among monozyzgotic twin pairs with one affected twin, approximately 90% of unaffected twins eventually develop the disease
First degree relative of patients with type 2 diabetes frequently have impaired nonoxidative glucose metabolism long before they develop type 2 diabetes
Ethnic predilection

29. Environment Low birth weight Gestational diabetes Prematurity
Sedentary lifestyle
High fat diet

30. Physiologic & Molecular basis of Diabetes
islet cell dysfunction
insulin resistance
Molecular
insulin receptor
Insulin signal transduction

31. Beta-Cell Function Is Abnormal in Type 2 Diabetes
A range of functional abnormalities is present
Abnormal oscillatory insulin release
Increased proinsulin levels
Abnormal insulin response
Progressive loss of beta-cell functional mass
Beta-cell dysfunction in patients with type 2 diabetes is manifested by a range of functional abnormalities. The normal pulsed oscillatory release of insulin is impaired, and proinsulin levels are increased due to inefficient conversion to insulin and quantitative reduction in insulin release.1,2
The first-phase insulin response is essentially absent, whereas the second-phase insulin response is slow and blunted.3,4 These abnormalities in the pattern of insulin response are accompanied by a progressive loss of beta-cell functional mass, leading to further deterioration.4
Adapted from Buchanan TA Clin Ther 2003;25(suppl B):B32–B46; Polonsky KS et al N Engl J Med 1988;318:1231–1239; Quddusi S et al Diabetes Care 2003;26:791–798; Porte D Jr, Kahn SE Diabetes 2001;50(suppl 1):S160–S163.
References
Buchanan TA. Pancreatic beta-cell loss and preservation in type 2 diabetes. Clin Ther 2003;25(suppl B):B32–B46. 
Polonsky KS, Given BD, Hirsch LJ et al. Abnormal patterns of insulin secretion in non-insulin-dependent diabetes mellitus. N Engl J Med 1988;318:1231–1239.
Quddusi S, Vahl TP, Hanson K et al. Differential effects of acute and extended infusions of glucagon-like peptide-1 on first- and second-phase insulin secretion in diabetic and nondiabetic humans. Diabetes Care 2003;26:791–798.
Porte D Jr, Kahn SE. -cell dysfunction and failure in type 2 diabetes: Potential mechanisms. Diabetes 2001;50(suppl 1):S160–S163.

32. First-Phase Insulin Response to IV Glucose Is Lost in Type 2 Diabetes
Normal
Type 2 Diabetes
120
120
100
100
Slide 9 80 80
First-Phase Insulin Response to IV Glucose Is Lost in Type 2 Diabetes
The normal beta-cell insulin response to IV glucose is biphasic. That is, there are 2 distinct phases noted:
The first (early) phase consists of a rapid increase in insulin secretion that occurs immediately after exposure of the beta cells to glucose. This phase is brief and is followed by a return to near basal levels within 10 minutes. The first phase is important in response to a rapidly shifting metabolic state, from the production of glucose to the disposal of glucose.1
A second (late) phase consists of a sustained increase in insulin secretion that begins 10 to 20 minutes after exposure to glucose. This phase can last for several hours.1
In the study shown on this slide, the release of insulin from beta cells was measured in normal subjects and patients with type 2 diabetes after they were given an intravenous glucose tolerance test with a 20-g bolus injection.2,3
Normal subjects showed a sharp first-phase insulin response.
However, patients with type 2 diabetes showed an absent first-phase response,2 with preservation of the second-phase insulin response.3
Sec6nd phase 0ay be de3ayed and red4ced
Plasma insulin (µU/mL)
Plasma insulin (µU/mL) 60 60 40 40 20 20
–30 30 60 90
120
–30 30 60 90
120
Time (min)
Time (min)
n=9 normal; n=9 type 2 diabetes.
Adapted from Pfeifer MA et al. Am J Med. 1981;70:579–588.
References:
1. Pratley RE, Weyer C. The role of impaired early insulin secretion in the pathogenesis of type II diabetes mellitus. Diabetologia. 2001;44:929–945.
2. Ward WK, Beard JC, Halter JB, Pfeifer MA, Porte D Jr. Pathophysiology of insulin secretion in non-insulin- dependent diabetes mellitus. Diabetes Care. 1984;7:491–502.
3. Pfeifer MA, Halter JB, Porte D Jr. Insulin secretion in diabetes mellitus. Am J Med. 1981;70:579–588.

33. Fewer beta cells/islet
Fewer Pancreatic Islets in Type 2 Diabetes
Normal
Compensation
More islets
Larger islets
More beta cells/islet
Larger beta cells
Nondiabetic Obesity
Slide 13
Fewer Pancreatic Islets in Type 2 Diabetes1
This slide shows the adult pancreatic morphology and illustrates the structural islet cell changes in type 2 diabetes.
In nondiabetic obesity, the pancreas appears enlarged because of the increased number and size of beta cells. Beta cells become larger in size to compensate for the higher metabolic demand, thereby maintaining normal cell function.
In the pancreas of subjects with type 2 diabetes the number of islets can decrease, the number of beta cells per islet is reduced, and amyloid plaques dominate.
Decompensation
Fewer islets
Fewer beta cells/islet
Amyloidosis
Type 2 diabetes
Adapted from Rhodes CJ. Science. 2005;307:380–384.
Reference:
1. Rhodes CJ. Type 2 diabetes—A matter of beta-cell life and death? Science. 2005;307:380–384.

34. Increased Beta-Cell Apoptosis Occurs in Type 2 Diabetes*
*p<0.05. Islet cell death was assessed by an ELISA method, which evaluates the cytoplasmic histone-associated DNA fragments. After incubation absorbance of samples was read spectrophotometrically.
Data obtained from pancreatic islets isolated from 6 T2DM organ donors and 10 nondiabetic cadaveric organ donors.
Adapted from Marchetti P et al. J Clin Endocrinol Metab. 2004;89:5535–5541.

35. Amylin Amylin co-secreted with insulin
Low amylin levels in type 2 diabetes
cause or effect is unclear

36. Depressed/delayed insulin response Nonsuppressed glucagon
Insulin and Glucagon Response to a Large Carbohydrate Meal in Type 2 Diabetes
Type 2 diabetes mellitus (n=12)*
Nondiabetic controls (n=11)
360
330
Meal
(mg/100 ml)
Glucose
300
270
240
110 80
A clinical study elucidated postprandial glucose, insulin, and glucagon dynamics in patients with type 2 diabetes mellitus (n=12) versus nondiabetic control subjects (n=11). The study also recruited 12 patients with type 1 (juvenile) diabetes; results for this group are not shown.1
After a large carbohydrate meal, mean plasma glucose concentrations rose from 228 mg/100 ml to a peak of 353 mg/100 ml in patients with type 2 diabetes mellitus, compared with an increase from 84 mg/100 ml to a peak of 137 mg/100 ml in nondiabetic subjects.1
In the 12 patients with type 2 diabetes mellitus, mean insulin values represent measurements from five patients in the group; insulin antibodies resulting from prior insulin therapy precluded insulin immunoassay in the other seven patients in the group. Insulin rose in normal subjects from a mean fasting level of 13 µU/ml to a peak of 136 µU/ml at 45 minutes after the meal. The insulin response in patients with type 2 diabetes mellitus was delayed and suppressed in comparison, increasing from a fasting level of 21 µU/ml to a peak of only 50 µU/ml at 60 minutes.1
Mean plasma glucagon levels declined significantly from the fasting value of 126 µµg/ml to 90 µµg/ml at 90 minutes (p<0.01) in the control group. In contrast, no significant fall in glucagon was observed in patients with type 2 diabetes mellitus; in fact, the mean plasma glucagon level rose slightly from the fasting level of 124 µµg/ml to 142 µµg/ml at 60 minutes and returned to 124 µµg/ml at 180 minutes.1
Therefore, this study showed that patients with type 2 diabetes mellitus had a delayed and suppressed insulin response and failed to exhibit normal postprandial declines in glucagon concentrations despite their marked hyperglycemia. These abnormalities contribute markedly to hyperglycemia both at the level of body tissues where insulin is not sufficient to drive glucose uptake and at the level of the liver where increased glucagon and decreased insulin spur the liver to release glucose into the blood.1
150
Depressed/delayed insulin response
120
Insulin
(µU/ml) 90 60 30
140
130
Nonsuppressed glucagon
Glucagon
(µµg/ml)
120
110
100 90
–60 60
120
180
240
Time (minutes)
*Insulin measured in five patients
Adapted from Müller WA et al N Engl J Med 1970;283:109–115.
Reference
Müller WA, Faloona GR, Aguilar-Parada E et al. Abnormal alpha-cell function in diabetes. Response to carbohydrate and protein ingestion. N Engl J Med 1970;283:109–115.

37. Incretin Function in Type 2 Diabetes
Secretion of GLP-1 impaired
Beta-cell sensitivity to GLP-1 decreased
Secretion of GIP normal (or slightly impaired)
Effect of GIP abolished or grossly impaired
Slide 15
Incretin Function in Type 2 Diabetes
In type 2 diabetes:
The secretion of GLP-1 is impaired1
The beta-cell sensitivity to GLP-1 is decreased2
The secretion of GIP is normal or slightly impaired1
The effect of GIP is abolished or grossly impaired3,4
Toft-Nielsen M-B et al. J Clin Endocrinol Metab. 2001;86:3717–3723; Kjems LL et al. Diabetes. 2003;52:380–386;
Vilsbøll T et al. Diabetologia. 2002;45:1111–1119; Vilsbøll T et al. J Clin Endocrinol Metab. 2003;88:4897–4903.
References:
1. Toft-Nielsen M-B, Damholt MB, Madsbad S, et al. Determinants of the impaired secretion of glucagon-like peptide-1 in type 2 diabetic patients. J Clin Endocrinol Metab. 2001;86:3717–3723.
2. Kjems LL, Holst JJ, Volund A, Madsbad S. The influence of GLP-1 on glucose-stimulated insulin secretion: Effects on ß-cell sensitivity in type 2 and nondiabetic subjects. Diabetes. 2003;52:380–386.
3. Vilsbøll T, Krarup T, Madsbad S, Holst JJ. Defective amplification of the late phase insulin response to glucose by GIP in obese type II diabetic patients. Diabetologia. 2002;45:1111–1119.
4. Vilsbøll T, Knop FK, Krarup T, et al. The pathophysiology of diabetes involves a defective amplification of the late-phase insulin response to glucose by glucose-dependent insulinotropic polypeptide—regardless of etiology and phenotype. J Clin Endocrinol Metab. 2003;88:4897–4903.

38. The Pathophysiology of Type 2 Diabetes Includes Islet Cell Dysfunction and Insulin Resistance
Glucagon
(Alpha cell)
Pancreas
Slide 6
The Pathophysiology of Type 2 Diabetes Includes Islet Cell Dysfunction and Insulin Resistance
The pathophysiology of hyperglycemia in type 2 diabetes involves the following defects: (1) insulin deficiency and excessive glucagon production; (2) insulin resistance; and (3) excess hepatic glucose output.1-3
Two pancreatic islet cell defects contribute to this pathology:
Beta cells produce insulin, which facilitates glucose entry into tissues and its subsequent storage or metabolism.4 In type 2 diabetes mellitus, a decline in functional beta-cell mass causes insulin deficiency, which in turn contributes to hyperglycemia.3-5
Alpha cells produce glucagon.6 Elevated glucagon levels promote increased hepatic glucose output.1 In type 2 diabetes mellitus, excess glucagon and diminished insulin drive hepatic glucose output and contribute to hyperglycemia.1
With decreased secretion of insulin, there is less uptake of glucose by muscle and adipose tissue.7
Insulin
(Beta cell)
Glucose uptake
Glucose output
Liver
Hyperglycemia
Muscle and
adipose tissue
Buse JB et al. In: Williams Textbook of Endocrinology. 10th ed. Saunders, 2003:1427–1483; Buchanan TA. Clin Ther. 2003;25(suppl B):B32–B46; Powers AC. In: Harrison’s Principles of Internal Medicine. 16th ed. McGraw-Hill, 2005:2152–2180; Rhodes CJ. Science. 2005;307:380–384.
Adapted from Kahn CR, Saltiel AR. Joslin’s Diabetes Mellitus. 14th ed. Lippincott Williams & Wilkins; 2005:145–168.
References:
1. Buse JB, Polonsky KS, Burant CF. Type 2 diabetes mellitus. In: Larsen PR, Kronenberg HM, Melmed S, et al, eds. Williams Textbook of Endocrinology. 10th ed. Philadelphia, Pa: Saunders; 2003:1427–1483.
2. Buchanan TA. Pancreatic beta-cell loss and preservation in type 2 diabetes. Clin Ther. 2003;25(suppl B):B32–B46. 
3. Powers AC. Diabetes mellitus. In: Kasper DL, Braunwald E, Fauci A, et al, eds. Harrison’s Principles of Internal Medicine. 16th ed. New York, NY: McGraw-Hill; 2005:2152–2180. 
4. Del Prato S, Marchetti P. Targeting insulin resistance and beta-cell dysfunction: The role of thiazolidinediones. Diabetes Technol Ther. 2004;6:719–731.
5. Rhodes CJ. Type 2 diabetes—a matter of beta-cell life and death? Science. 2005;307:380–384.
6. Williams G, Pickup JC, eds. Handbook of Diabetes. 3rd ed. Malden, Mass: Blackwell Publishing; 2004.
7. Porte D, Kahn SE. The key role of islet dysfunction in type 2 diabetes mellitus. Clin Invest Med. 1995;18:247–254.

39. Insulin Resistance
Genetics
Age
Weight
adipokines

40. Intra-abdominal adiposity is a major contributor to insulin resistance
IAA = high risk fat
Associated with
inflammatory markers
(C-reactive protein) 
Dyslipidaemia
DM2
Increased
cardiometabolic
risk
Free fatty
acids 
Insulin
resistance
This slide summarises the relationships between intra-abdominal adiposity (IAA) and increased cardiometabolic risk. Intra-abdominal adiposity drives the progression of multiple risk factors directly, through the secretion of excess free fatty acids and inflammatory adipokines, and decreased secretion of adiponectin. The important contributions of IAA to dyslipidaemia and insulin resistance provide an indirect, though clinically important, link to the genesis and progression of atherosclerosis and cardiovascular disease.
The location of excess IAA is an important determinant of cardiometabolic risk. IAA is associated with insulin resistance, hyperglycaemia, dyslipidaemia, hypertension, and prothrombotic/proinflammatory states. Excess IAA typically is accompanied by elevated levels of C-reactive protein (CRP) and free fatty acids (FFAs), as well as decreased levels of adiponectin. Elevated CRP is an indicator of inflammation. Abdominal obesity has been shown to be associated with the inflammation cascade, with adipose tissue expressing a number of inflammatory cytokines. Inflammation is now believed to play a role in the development of atherosclerosis and type 2 diabetes. Elevated levels of CRP are considered to be predictive of cardiovascular disease and insulin resistance.
Elevated FFA levels appear to play a significant role in the cause of insulin resistance. It has been suggested that elevated FFAs and intracellular lipids inhibit the insulin signaling mechanism, leading to decreased glucose transport to muscle. FFAs also play a mediating role between insulin resistance and β-cell dysfunction, indicating that a reduction in FFA level could be a desirable therapeutic target.
Adiponectin is an adipose tissue-specific circulating protein which is involved in the regulation of lipid and glucose metabolism. Adiponectin has been shown to be reduced in adults with obesity and type 2 diabetes. In non-diabetics, hypertriglyceridaemia and low HDL-cholesterol have been shown to be associated with low plasma adiponectin concentrations.
All of these components help to explain why excess abdominal adiposity is considered to be a great threat to cardiovascular and metabolic health.
Secretion of
adipokines
(↓ adiponectin) 
Inflammation
IAA: intra-abdominal adiposity
Kershaw EE et al, 2004; Lee YH et al, 2005; Boden G et al, 2002
Kershaw EE, Flier JS. Adipose tissue as an endocrine organ. J Clin Endocrinol Metab 2004;89:2548–2556.
Lee YH, Pratley RE. The evolving role of inflammation in obesity and the metabolic syndrome. Curr Diab Rep 2005;5:70–75.
Boden G, Shulman GI. Free fatty acids in obesity and type 2 diabetes: defining their role in the development of insulin resistance and beta-cell dysfunction. Eur J Clin Invest 2002;32:14–23.

41. endocannabinoid system dysregulation
Feeding
ECS
Weight-dependent
Weight Independent
ECS
Endocannabinoid system
Visceral fat
Weight
CB-1 blockade
Type 2 diabetes
Dyslipidaemia
TG-rich VLDL-C
Small, dense LDL-C
Low HDL-C
Lipolysis
CETP, lipolysis
Hepatic insulin resistance
Hepatic glucose output
Peripheral insulin resistance
Adiponectin
This slide summarises the central and peripheral actions that contribute to the beneficial cardiometabolic profile of rimonabant.
Normally, the central nervous ECS activates to promote feeding behaviour as required, and then becomes quiescent. However, the continued intake of highly palatable, high-energy food common in developed nations sets up a vicious cycle where a chronically overactive ECS in key areas of the brain helps to maintain a high level of energy intake. This inevitably leads to the development of excess intra-abdominal adiposity which increases the risk of dyslipidaemia and type 2 diabetes.
The peripheral ECS is also involved in the regulation of metabolism in the periphery. Overactivity of the ECS in intra-abdominal adipocytes promotes the secretion of a range of bioactive substances, including:
Decreased secretion of the cardio-protective hormone, adiponectin, which increases insulin resistance and cardiovascular risk
Increased free fatty acid delivery to the liver which promotes hepatic insulin resistance, hyperglycaemia and atherogenic dyslipidaemia
Large and well-designed clinical trials in patients with multiple cardiometabolic risk factors (the RIO programme) have shown that selective blockade of central and peripheral CB1 receptors by rimonabant improves multiple cardiometabolic risk factors by countering the adverse effects of the overactive ECS. Moreover, the therapeutic efficacy of rimonabant on indices of cardiometabolic risk arises through a direct effect on peripheral tissues including adipocytes and liver, in addition to effects secondary to weight loss. Indeed, about half of the beneficial effects of rimonabant on levels of adiponectin, HbA1c, HDL-cholesterol, triglycerides, insulin and other cardiometabolic risk factors were not attributable to weight loss alone in the RIO programme, suggesting a direct metabolic effect of the drug.
Portal circulation
Liver
FFA
ECS
ECS
Modified from: Lam TKT, 2003; Carr DB, 2004; Eckel R, 2005; Pagotto U, 2005; Di Marzo V et al, 2005
FFA=free fatty acids
CETP=cholesterol
ester transfer protein
Lam TKT et al. Mechanisms of free fatty acid-induced increase in hepatic glucose production. Am J Physiol Endocrinol Metab 2003;284:E863–73.
Carr DB, Utzschneider KM, Hull RL et al. Intra-abdominal fat is a major determinant of the National Cholesterol Education Program Adult Treatment Panel III criteria for the metabolic syndrome. Diabetes 2004 Aug;53(8):2087–94.
Eckel R, Grundy S, Zimmet P. The metabolic syndrome. Lancet 2005;365(9468):1415–28.
Pagotto U, Pasquali R. Fighting obesity and associated risk factors by antagonising cannabinoid type 1 receptors. Lancet 2005;365:1363–4.
Di Marzo V, Matias I. Endocannabinoid control of food intake and energy balance. Nature Neuroscience 2005;8:585–9.

42. Insulin Action decrease in number of insulin receptors
any disruption in the transcription or transduction of insulin signaling pathway

44. Summary
Glucose metabolism is tightly regulated to maintain desirable glucose levels
Glucose dysregulation leads to progressive dysglycemia from prediabetes to frank diabetes
The pathophysiology of type 2 diabetes is complex.
Involves multiple physiologic and molecular disturbances influenced by multiple genes and environmental factors
This offers multiple target sites for therapy and explains the complexity of treatment of DM2