1. Insulin and Non Insulin Treatments of Diabetes Mellitus Orla Mahony March 2012

2. Non-insulin treatments Sulfonylureas Biguanides Chromium and vanadium Acarbose Incretinmimetics Amylin

3. Sulfonylureas (Glipizide) Enhance insulin secretion Bind to the K ATP channel on ß cell Glipizide in 50 diabetic cats; Feldman 1997 Improvement in 30% of new DM cats Side effects; hypoglycemia, vomiting, inc LE’s and icterus (<15%) Recommend for owners unable to give insulin, or for cats with intermittent transient DM or for cats exquisitely sensitive to insulin Glipizide may increase amyloid deposition,Hoenig et al, 2000

4. Sperling M. N Engl J Med 2006;355:507-510 Regulation of Insulin Secretion

5. Gloyn A et al. N Engl J Med 2004;350:1838-1849 Schematic Representation of the Pancreatic Beta Cell, Illustrating the Role of the ATP-Sensitive Potassium (KATP) Channel in Insulin Secretion

6. Biguanides (Metformin/Glucophage) Increases translocation of GLUT 1 & 4 transporters in different types of cells Inhibits hepatic gluconeogenesis and glycogenolysis Increases muscle glucose metabolism by enhancing muscle insulin sensitivity Does not stimulate insulin secretion (no hypoglycemia) Can rarely cause (fatal) lactic acidosis by stimulating intestinal conversion of glucose to lactate Decreased hepatic synthesis of VLDL Metformin & sulfonylureas produce similar results Weight gain rare with metformin

7. Metformin in Cats Nelson et al, JVIM 2004 Study involved normal and diabetic cats Disappointing results, 3 failed to respond and 1 died Death undetermined Side effects included lethargy, inappetence, vomiting, and weight loss

8. Chromium and Vanadium Transition-metals Activate glucose metabolism within the cell Insulin sensitizers Chromium is an essential cofactor for insulin function and chromium deficiency results in insulin resistance Schachter et al 2001; Chromium had no effect in diabetic dogs Appleton DJ et al 2002; Improved glucose tolerance in normal weight, healthy cats given chromium Greco D states low doses of vanadium (0.2mg/kg/day) lowers glucose and fructosamine in early T2DM cats Transient anorexia Long term accumulation could lead to CRF (1 cat)

9. Acarbose Complex oligosaccharide of microbial origin Competitively inhibits α- glucosidases in GIT Acarbose improved glucose control in 6 diabetic dogs but ⅓ rd had diarrhea and weight loss Nelson et al 2000 Diabetic cats fed a low CHO diet had a similar response to cats on low CHO diet and acarbose Mazzaferro et al JFMS 2003

10. Incretin Hormones Incretins – GIP, glucose-dependent insulinotropic polypeptide – GLP-1, glucagon like peptide 1 Incretin effect

11. The incretin effect is the increased insulin secretion which occurs with food ingestion as a result of release of incretin hormones, primarily GIP and GLP-1. Oral GTT versus i/v GTT

12. Secreted by K cells of duodenum in response to food Primary action is stimulation of glucose- dependent insulin secretion May stimulate β cell proliferation and inhibit apoptosis Inactivated by Dipeptidyl-peptidase IV (T½ 7 mins) GIP Glucose-dependent insulinotropic polypeptide

13. Glucagon-like peptide 1 GLP-1 Produced by L-cells (primarily distal SI) Secreted in response to nutrient ingestion Stimulates glucose-dependent insulin secretion (via G protein coupled R, ↑ cAMP, ↑ iCa, exocytosis) Effect on insulin secretion may also be via autonomic nerves βcell proliferation and neogenesis in rodents Inhibits apoptosis in human tissue cultures Extensively metabolized by the enzyme DPP-4

15. Other Actions of GLP-1 I nhibits glucagon secretion Delays gastric emptying Reduces food intake Cardioprotective effects Renal protective effects Modulatory role in HPit axis?

16. Incretins in cats GLP-1 secretion is stimulated by glucose, amino acids and lipids K and L cells throughout small and large GI Potentiation of insulin secretion is minimal with oral glucose and is mediated by GLP-1, not GIP GIP secretion is stimulated by amino acids and lipids

17. DPP-4 / CD26 Serine protease Degrades GLP-1 and GIP Ubiquitous in tissues and blood Only 15% active form reaches systemic circulation, therefore need to measure active and inactive forms (total) to evaluate GLP -1 secretion GIP more than GLP also degraded renally

18. Loss of the incretin effect in T2DM and obesity Loss of β cell response to GIP Decreased secretion of GLP-1 (2° to DM) Impaired β cell sensitivity to GLP-1 Glucose stimulated GLP-1 concs. higher in lean vs obese cats, Hoenig 2010

19. Implications Treatment with GIP unhelpful Treatment with native GLP-1 unhelpful (T1/2 2 mins) Treatment with GLP-1 analogs Dipeptidyl peptidase-4 inhibitors

20. GLP-1 mimetics Exenatide (Byetta), synthetic exendin-4 8 hr DOA, biologic effects up to 15 hrs Restores early insulin response As effective as insulin glargine but fewer side effects One report of pancreatitis Antibody formation common Promotes beta cell regeneration and differentiation (rats)

21. Amylin/Pramlintide Synthetic analog of amylin (IAPP) that does not form amyloid Approved for treatment of T1 and T2 DM 2005 Slows gastric emptying Suppresses post prandial hyperglycemia Decreases postprandial hyperglucagonemia Improves glycosylated Hb conc n Weight loss (desirable) Side effects include nausea and hypoglycemia

22. Amylin in cats Amylin reduces glucagon in normal cats Vet Journal 2009, Furrer et al Study used rat amylin, and showed mild decreases in glucagon following arginine, glucose and meal stimulation. Short acting May be more beneficial in diabetic cats

23. Insulins Humulin NPH U100 Insulin glargine/Lantus U100 Detemir U100 PZI U40 Porcine Lente U40

24. All mammalian insulin is similar 51 AA’s in 2 polypeptide chains 21 AA A-chain 30 AA B chain

26. Formulation Short-acting Intermediate-acting Long-acting Sometimes mixed together Do not mix glargine or Zn insulins with other insulins

27. Lentes (semilente, lente, ultralente) all have _____ to delay absorption NPH has _____ to delay absorption PZI has _____ and _____ to delay absorption 1 unit of insulin = 36 mcg of insulin Use U40 syringes with U40 insulin (40 IU/ml) Vetsulin (porcine lente) and PZI are U40 (40 IU/ml) insulins

28. ½ unit scale syringes are available (diabetes care, 31g, 30u short needle) Vial syringe guides Syringe magnifiers Keith et al showed drawing up 1-2 unit doses inaccurate with syringes

29. Humulin NPH U100 / Isophane (neutral protamine Hagedorn) Contains fish protein, protamine, to delay absorption Intermediate insulin Recommended for dogs Give BID Goeders et al 1987; dogs Time for NPH to return to baseline; 8 hrs Wallace et al 1990; cats Peak insulin concentraton 1.6 hrs, DOA 7.7 hrs.

30. Humulin NPH in diabetic dogs Palm et al JVIM 2009;23:50-55 10 well controlled DM dogs, <1U/kg bid, fed high fiber diets (wd 7, euk wt control 3, nutro wt control) BG and insulin measured q 30mins for 2hrs, then q 2hrs for up to 10hrs Insulin DOA 4-10hrs (T 0 bg to time for bg to reach 70% of baseline), 4 dogs ≥ 10 hrs

31. Mean % of insulin-induced glucose suppression 50% Post-prandial hyperglycemia in 5 dogs, resolved within 2.2hrs

32. Insulin Glargine/Lantus Human recombinant insulin with AA substitutions and additions Shift in isoelectric pt.,soluble at pH 4 Insulin precipitates into hexamers at interstitial pH of 7.4 Hexamers slowly form active insulin monomers Gradual onset, long duration

33. Insulin glargine/Lantus

34. Insulin Glargine/Lantus Glucose nadir healthy cats; glargine (14 hrs), PZI (biphasic 4, 14 hrs), lente (5 hrs) Marshall et al, J vet Pharmacol Therap 2008 SID not inferior to bid in normal cats, Marshall 08 BG suppressed @ 24 hrs in 1/2 of sid or bid cats Higher remission rate with glargine (8/8) vs PZI (3/8) vs lente (2/8) newly dx diabetics, dm canned diet Marshall et al, JFMS 2009 Glargine SID is as effective as lente BID Weaver et al, JVIM 2006

35. Use of insulin glargine in dogs with DM Fracassi Vet Rec 2012 12 dogs, 9 new diabetics, 3 tx with vetsulin 3 intact females (spayed within 3 wks) Glargine; 0.27 U/kg (0.18-0.53) at start and 0.6 U/kg (0.11-1.07) at end Nadir varied (0-12), 6, 8, 10 hrs on average BG<90 in 18% of curves, no clinical hypogly Varied diet

36. BGCs done before, 1, 2, 4, 8, 12, 24 weeks 12 hr curves, dog usually fed and inj. @ hosp 58% good control (mean bg < 230) 33% moderate control (mean bg 230-300) 1% poor control (mean bg >300) Fructosamine (good 25%, moderate 58%, poor 17%)

37. Discussion Results similar to NPH and vetsulin studies although vetsulin study stated 75% good control No clinical hypoglycemia Clear nadir (unlike in people, peakless) but unpredictable May have needed 24 hr curve to determine nadir

38. Insulin Detemir/Levemir® U100 Insulin Approved in US 2006 Long-acting,synthetic insulin analogue Similar to glargine Slow release due to formation of hexamers as well as binding to albumin at the injection site and in the circulation( inc. availability to liver w fenestrated vessels) More consistent glucose lowering than with lantus Reduced risk of hypoglycemia? 2 studies of use in cats Max dose 30% lower than lantus, rarely > 4U

39. Detemir is acetylated with myristic acid(saturated FA found in dairy products), allowing hexamers to form at a neutral pH, and importantly allowing the insulin to bind to albumin, resulting in a very slow, smooth delivery of insulin such that once daily administration is all that is needed in people

40. ProZinc™ Protamine zinc recombinant-human insulin U40 insulin, use with U40 syringes Preliminary study of PZIR for the Tx of DM in cats Vet Ther 2009;10:24-28 – 50 cats, switched from PZI VET to PZIR same dose and interval, no significant differences in wt, fruct days 15, 30 compared to day 0.

41. Field safety and efficacy of PZIR bid for Tx of DM in cats JVIM 2009;23:787-793 133 cats, 13 previously diagnosed 9hr bg curve done day 0, 7, 14, 30, 45. Fruct done day 0, 14, 30, 45 Hypoglycemia (<80) detected in 64% of cats Clinical signs in 2, possibly 26 other episodes On day 45, 34% of cats had low glu nadir, mean bg or fruct on day 45, some were probably going into remission Bid admin, nadir 5-7, bg increasing by 9hrs

42. PZI and Dogs?

43. Pharmacokinetics and Pharmacodynamics of Glargine, Beef-Pork PZI & Pork Lente Insulin in Healthy Dogs Stenner ACVIM abs 2004 Onset of Action; lente (0.6 hr), PZI (3 hrs) Glargine (2.2 hrs) Glucose Nadir; lente (2.4 hrs) glargine (5.7 hrs) PZI (6.4 hrs) DOA lente (10 hrs) glargine (13 hrs), PZI (19 hrs) Peak insulin; lente (1.2 hrs), glargine (0.5-6 hr), PZI (0.5 hr) Glargine had no glucose lowering effect in 2/9 dogs Glargine unpredictable in dogs PZI glucose lowering effect in 9/9 dogs but Ab’s to beef insulin a potential concern

44. Efficacy of rhPZI in dogs with DM Maggiore et al JVIM 2012 6 new diabetics, 11 previous diabetics 10 hr bg curve day 7, 14, 30, 60 Fructosamine, spec cPL 0.25-0.5 U/kg initial dose Goal; bg between 80-300, nadir 80-150

45. Results LBG 10h 80-150 n= 4, >200 n=11, <80 n=2 No significant change betw day 1 and 60 LBG 10h >200 in 42 of 68 bg curves LBG 10hr occurred 2-12 hrs post inj, and in 54% was at start or end of curve 7 hypoglycemic events (3 clinical, 4 nonclinical during curves)

46. Results MBG 299±115 vs 457±38 MBG decreased in 16 dogs Fructosamine 478±83, vs 557±104 Fruct decreased in 11/17 dogs PuPd improved in 14Body wt stable or increased in 16

47. Inconsistency in BG concs from day to day Prolonged duration of rhPZI effect Somogyi response Pharmacokinetic variability of rhPZI Once daily administration? High dose requirements Starting dose of 0.5U/kg Median end dose of 1U/kg (0.4-1.5)

48. Porcine Lente Insulin (Vetsulin) U40 40 IU/ml Mixed insulin Zn suspension 30% amorphous semilente rapidly absorbed 70% crystalline Zn ultralente slowly absorbed Intermediate insulin Licensed for use in dogs Less potent than NPH but longer acting

49. Vetsulin continued DOA 14 to 24 hrs Many dogs have 2 peaks (4, 11 hrs) of insulin activity (Graham et al, JSAP 1997) In some dogs earlier peak is largest Dose ¼ to ½ u/kg SQ BID U40; more accurate dosing in small dogs Administer BID (Munroe et al, JVIM 2005) (Horn et al, Aust Vet J 2001)

51. Vetsulin in Cats Parmacology of Vetsulin in diabetic cats Martin et al, JFMS 2001 Time to peak insulin 2 hrs Time to glucose nadir 4 hrs Time for insulin concentration to return to baseline – 8 hrs Give BID (may even need TID) Similar pharmacological properties to beef-pork NPH Shorter DOA compared with Humulin and beef/pork UL and beef-pork PZI Antibodies to porcine insulin possible Poor absorption possible

52. Amino Acid Differences between species A8A10A18 B30 DogThrIleAsnAla PigThrIleAsnAla HumanThrIleAsnThr CowAlaValAsnAla CatAlaValHisAla Feldman & Nelson 3 rd Ed p496