Jens J. Holst

No Effect of Aprotinin (Trasylol™) on Degradation of Exogenous and Endogenous Glucagon in Human, Mouse and Rat Plasma

Traditionally, aprotinin (Trasylol™) has been added to plasma samples prior to glucagon analysis. However, the evidence for the need of aprotinin is sparse and based on results obtained when radioimmunoassay (RIA) techniques were still in their infancy. Using RIAs directed against both the C-terminus and a mid-region of glucagon, we challenged the classical view that aprotinin is necessary. Glucagon concentrations in pools of human, mouse and rat plasma (n=30, 25 and 16 of each, respectively) with and without addition of increasing amounts of exogenous glucagon (5, 10, 20, 40 and 60 pM) were similar irrespective of whether or not aprotinin had been added. To investigate whether individual variation occurs in human samples, we measured plasma from 20 patients with gastrointestinal diseases and 20 healthy subjects with or without addition of aprotinin. Again, measured amounts of glucagon, endogenous or added, were not affected by the presence of aprotinin. The effect of aprotinin, present at blood sampling or added later (30 and 60 minutes), on endogenous glucagon values was investigated in T2DM patients (n=5), before and after insulin-induced hypoglycemia. There were no differences between the four treatments. In conclusion, we found no support for use of aprotinin for prevention of glucagon degradation.

Coming of Age for the Incretins

The incretin hormones, glucose-dependent insulinotropic polypeptide (GIP) and glucagon-like peptide-1 (GLP-1), may be responsible for up to 70% of postprandial insulin secretion. In type 2 diabetes (2DM), the incretin effect is severely reduced. Secretion of GIP is normal, but its effect on insulin is lost. GLP-1 secretion may be impaired, but its actions may restore insulin secretion to near normal levels. Substitution therapy with GLP-1 might therefore be possible. GLP-1 actions include potentiation of glucose-induced insulin secretion, up-regulation of insulin and other β-cell genes, stimulation of β-cell proliferation and neogenesis and inhibition of β-cell apoptosis, inhibition of glucagon secretion, inhibition of gastric emptying, and inhibition of appetite and food intake. It may also have cardioprotective and neuroprotective actions. These actions make GLP-1 particularly attractive as a therapeutic agent for 2DM, but GLP-1 is rapidly destroyed in the body by the enzyme, dipeptidyl peptidase IV (DPP-IV). Clinical strategies therefore include (i) the development of metabolically stable activators of the GLP-1 receptor and (ii) inhibition of DPP-IV. Orally active DPP-IV inhibitors are currently undergoing clinical trials, and recent clinical studies have provided long-term proof of concept. Metabolically stable analogs/activators include the structurally related lizard peptide, exendin-4, or analogs thereof, as well as GLP-1-derived molecules that bind to albumin and thereby assume the pharmacokinetics of albumin. These molecules are effective in animal experimental models of 2DM and have been employed successfully in clinical studies of up to 82 weeks’ duration, and exendin-4 has just been approved for add-on therapy of 2DM.

19. Efficacy and Safety of Liraglutide Added to Insulin in Type 1 Diabetes: The LIRA-1 Trial (277-OR)

SamenvattingWeight gain and hypoglycemia are common side effects to insulin therapy in type 1 diabetes (T1D). The combination of insulin and glucagon-like peptide-1 receptor agonist (GLP-1RA) therapy has proven effective in reducing weight gain and insulin dose in type 2 diabetes. This 26-week trial is the first randomized, double-blinded, placebo controlled study to evaluate efficacy and safety of GLP-1RA treatment in poorly controlled, overweight patients with T1D. One hundred patients with T1D, HbA1c > 64 mmol/mol and BMI > 25 kg/m2, were randomized to liraglutide 1.8 mg (LIRA) or placebo added to intensive insulin therapy. Mean baseline characteristics were similar between groups (LIRA; placebo ± SD) age 47 ± 13; 49 ± 12 years, HbA1c 73 ± 8;73 ± 8 mmol/mol, daily insulin dose 75 ± 30; 74 ± 26 IU/day and body weight 93.4 ± 14.2; 94.0 ± 12.5 kg except diabetes duration 20 ± 12; 25 ±12 years. After 12 weeks, LIRA reduced HbA1c, body weight and daily insulin dose compared with placebo. At end of treatment no difference in HbA1c between groups was found. Body weight and daily insulin dose remained reduced in the LIRA group. Frequency of hypoglycemia did not differ between groups. Nausea occurred more frequently with LIRA than placebo (48% vs. 7%). In conclusion, LIRA added to insulin treatment reduced body weight and daily insulin dose in overweight, poorly controlled patients with T1D, but did not improve HbA1c compared with placebo at end of treatment.

PS14 - 68. Differential effects of antibiotics on bile acid metabolism, intestinal microbiota composition and insulin resistance in obese humans; a randomised controlled trial

Recent data in animal models reveal that obesity is associated with substantial changes in composition and metabolic function of gut microbiota.