Diabetes and the Surgical Patient Dr. Cathy Code October 14, 2008

Objectives Review the various agents used to treat diabetes Discuss the impact of surgery on diabetes Provide a framework for the preoperative assessment of a diabetic patient Provide a practical approach to the perioperative management of diabetes

Diabetes Common chronic disorder Associated with both macrovascular and microvascular complications More surgical interventions A diabetic has a 50% chance of requiring a surgery in their lifetime 20% of surgical patients have diabetes

Diabetes Complex interaction b/w operative procedure, type of anesthesia, and postoperative factors Diabetic patient requires careful assessment prior to surgery Increased length of hospital stay and cost Increased risk of periop infection and postop CVS morbidity and mortality

Type 1 DM Primarily a result of pancreatic beta cell destruction Absolute insulin deficiency Prone to ketoacidosis Autoimmune process vs idiopathic Requires ongoing insulin treatment

Type 2 DM Predominant abnormality is insulin resistance May be treated with diet, OHG and or insulin Others: Diseases of pancreas Endocrinopathies Drugs

Oral Hypoglycemics Acarbose Sulfonylureas Meglitinides Alpha-glucosidase inhibitor Sulfonylureas Insulin secretagogues ex. Glyburide (Diabeta), Gliclazide (Diamicron) Rapid BG lowering potential Meglitinides ex. Repaglinide (GlucoNorm)

Oral Hypoglycemics Metformin TZDs Negligible hypoglycemic risk CI in renal failure (GFR < 30ml/min) and hepatic failure TZDs ex. Pioglitazone (Actos), Rosiglitizone (Avandia) Avoid in CHF ? Association with increased cardiovascular events

Insulin Type Onset Peak Duration Prandial Insulins Rapid–acting Aspart (Novorapid) Lispro (Humalog) 10-15 mins 1-1.5 hrs 1-2 hrs 3-5 hrs 3.5-4.5 hrs Short-acting Humulin R Novolin Toronto 30 mins 2-3 hrs 6.5 hrs Basal Insulins Intermediate-acting Humulin N Novolin NPH 1-3 hrs 5-8 hrs Up to 18 hrs Long-acting Detemir (Levemir) Glargin (Lantus) 90 mins n/a Up to 24 hrs

Preoperative Assessment: Focus on cardiopulmonary risk assessment and modification CHD more common in diabetics Associated conditions: HTN Obesity CKD Cerebrovascular disease Autonomic neuropathy

Preoperative Assessment: Key elements: Type of DM Longterm complications Baseline glycemic control Assessment of hypoglycemia Diabetic meds Other meds Characteristics of surgery Type of anesthetic

Preoperative Testing: Baseline ECG Renal Function Hgb A1C Determination of chronic glycemic control Elevated levels may predict a higher rate of postop infections Noninvasive cardiac testing if indicated

Impact of Surgery Surgery and anesthesia lead to a neuroendocrine stress response Counterregulatory hormones: Epinephrine Glucagon Cortisol Growth Hormone Inflammatory cytokines

Impact of Surgery Leads to: Hyperglycemia and possibly ketosis Insulin resistance Decreased peripheral glucose utilization Impaired Insulin secretion Increased lipolysis Protein catabolism Hyperglycemia and possibly ketosis

Impact of Surgery Varies per individual Influenced by type of anesthesia GA > spinal anesthesia Extent of surgery Major vs minor Postoperative factors Sepsis, hyperalimentation, steroid use

Goals Maintenance of fluid and electrolyte balance uncontrolled DM leads to volume depletion from osmotic diuresis Prevention of ketoacidosis Type 1 diabetics are insulin deficient and require continuous insulin administration

Goals Avoidance of marked hyperglycemia Avoidance of hypoglycemia DKA in Type 1 diabetics Nonketotic hyperosmolar state in Type 2 diabetics Avoidance of hypoglycemia Potentially a life threatening complication Cardiac arrhythmias Cognitive deficits and neurologic sequelae

Glycemic Targets Exact target unclear Limited evidence and lack of controlled trials except…. Coronary bypass surgery, IV insulin to maintain BS 5.5-10.0, associated with less sternal wound infection and mortality Surgical ICU patients with hyperglycemia, IV insulin to maintain BS 4.5 – 6.0, reduced mortality and morbidity

Glycemic Targets Meta-analysis of RCTs in JAMA 2008 29 RCTs of tight glycemic control in critically ill patients in an ICU setting No evidence of improved patient oriented outcomes Found increased frequency in potentially harmful hypoglycemia in patients treated with glucose control

Glycemic Targets Otherwise…… Published guidelines collectively propose attempting to achieve reasonable normoglycemia 2008 CDA guidelines: Perioperative glycemic levels should be maintained between 5.0 – 11.0 avoid hypoglycemia Grade D, consensus

Diabetes Management: Early perioperative phase Several various strategies No consensus on optimal therapy Aim to have surgery early in am to minimize disruption of their management while NPO

Diabetes Management: Early perioperative phase T2DM, diet alone: Usually do not require any therapy periop Supplemental short acting insulin (regular, humalog, novorapid) may be given by sliding scale if levels above target Check BS preop and postop IV dextrose not required unless insulin is administered and patient NPO

Diabetes Management: Early perioperative phase T2DM on OHG: Hold OHG am of OR Most patients with good control will not require insulin for short surgical procedures Short-acting supplemental insulin by sliding scale can be used for hyperglycemia Restart OHG when patients resume eating Hold metformin is patient has developed renal impairment

Diabetes Management: Early perioperative phase Type 1 DM or insulin treated Type 2 DM: For short, non complex procedures patients can usually continue SC insulin Continue long-acting insulin while NPO and on IV dextrose For patients with tight control or prone to hypoglycemia, reduce evening/hs insulin night before surgery

Diabetes Management: Timing of Procedure Minor, early morning procedures, breakfast only delayed patients can take their insulin after surgery Procedures where breakfast and lunch missed Omit short-acting insulin and give 1/2 to 2/3 of long-acting insulin OR Take 1/3 to 1/2 of total morning dose as long-acting only OR SC insulin pump, continue basal rate OR Start dextrose containing IV solution

Diabetes Management: Timing of Procedure Long and complex procedures IV insulin is required for Type 1 diabetics and Insulin requiring Type 2 diabetics Safe Easily titrated with a short ½ life (5 – 10 minutes) Usually started morning prior to surgery IV insulin infusion algorithms

Diabetes Management: Late postoperative phase Preoperative diabetes treatment can be reinstated once the patient is eating well Metformin should not restart in renal insuff Sulfonylureas should only be started after patient eating well, consider stepwise approach Avoid TZDs in CHF or problematic fluid retention

Diabetes Management: Late postoperative phase Insulin infusions should be continued until solids well tolerated then switch to SC insulin For patients on SC insulin, continue IV dextrose until patient eating well

Sliding Scales Often used to correct elevated levels Problematic if used as the sole method of diabetic treatment Reactive process, causes wide fluctuation in serum glucose Should never be the sole method of treatment in T1DM due to risk of ketosis

Example - standard Regular, Humalog, Novorapid Insulin, TID, ac meals BS reading Insulin 0 – 4.0 No insulin, give sugar 4.1 – 8.0 No insulin 8.1 – 11.0 2 units 11.1 – 14.0 4 units 14.1 – 16.0 6 units 16.1 – 18.0 8 units 18.1 – 20.0 10 units > or = 20.1 Call MD

Example – Insulin sensitive Elderly, lean patients or individuals with renal or liver dysfunction BS reading Insulin 0 – 4.0 No insulin, give sugar 4.1 – 8.0 No insulin 8.1 – 11.0 11.1 – 14.0 2 units 14.1 – 16.0 3 units 16.1 – 18.0 4 units 18.1 – 20.0 5 units > or = 20.1 Call MD

Example – Insulin resistant Obesity, treatment with glucocorticoids BS reading Insulin 0 – 4.0 No insulin, give sugar 4.1 – 8.0 No insulin 8.1 – 11.0 4 units 11.1 – 14.0 8 units 14.1 – 16.0 12 units 16.1 – 18.0 16 units 18.1 – 20.0 20 units > or = 20.1 Call MD

Special Considerations Glucocorticoids Used to treat many disorders, given in “stress” doses perioperatively Can worsen existing DM and trigger hyperglycemia in others Augment hepatic gluconeogenesis, inhibit glucose uptake, and alter receptor function 2 to 3 fold increase in total daily insulin can be required with stress doses

Special Considerations Hyperalimentation TPN increase blood glucose Increase basal insulin, add insulin to TPN NG feeds Either a IV insulin infusion or BID long-acting insulin + sliding scale Make sure to change insulin if feeds changes to bolus

Case examples Case #1 Mr S, 58 yr old man with newly dx’d colorectal Ca Scheduled for Right Hemicolectomy Hx of T2DM maintained on metformin and Novolin NPH 16u SC qam and 10u SC qpm Hx of controlled HTN, stable angina How should this patient be managed?

Case #1 cont…. Preop Postop Bowel prep and NPO at midnight Hold Metformin morning of OR Give 8u of NPH insulin am of OR Provide IV dextrose during OR Postop Hold metformin until eating well Give 16u of NPH qam and 10u of NPH qpm Continue IV dextrose until eating well Insulin sliding scale TID prn with meals

Case examples Case #2 Ms P, 36 yr old female with perforated DU awaiting in ER for urgent OR Type 1 DM for 15 yrs complicated by retinopathy, neuropathy, and gastroparesis On Levemir 20u BID and Novorapid sliding scale with meals by carb counting, average 4-6u per meal How should this patient be managed?

Case #2 cont.. Preop Postop NPO, frequent glucoscans IV regular insulin starting at 2u/hr IV dextrose Postop Continue IV insulin and dextrose until eating well and overlap with SC insulin Watch for nausea and vomiting given hx of gastroparesis

Take Home Message Common chronic health problem Needs to be managed closely perioperatively Associated with increased perioperative risk Not aiming for perfect glucose measurements but instead safe measurements