Exendin-4 normalized postcibal glycemic excursions in type 1 diabetes.

Exendin-4 is a reptilian peptide that activates the mammalian receptor for truncated glucagon-like peptide 1 (tGLP-1) with relatively prolonged actions. Exendin-4 and tGLP-1 can reduce blood glucose levels by stimulating insulin secretion, inhibiting glucagon secretion, and delaying gastric emptying. We tested a range of doses of exendin-4 on postcibal glycemic excursions in nine volunteers with type 1 diabetes, all with negligible endogenous insulin secretion, in paired comparisons with vehicle in at least six volunteers with each of six doses. We established a side effect-free dose and an appropriate antecibal time for sc administration of exendin-4. Subsequently, exendin-4 was administered 15 min before breakfast, with usual insulin, to eight of the volunteers. Acetaminophen was ingested with the meal as an indicator of gastric emptying. The mean plasma glucose excursion was reduced by 90%, falling into the normal range, after breakfast, whereas plasma pancreatic polypeptide, glucagon, and acetaminophen levels were reduced, and insulin levels were not affected. Thus, normalization of postcibal glycemia was associated with delayed gastric emptying and suppression of glucagon secretion, without increased secretion or blood levels of insulin. We suggest that tGLP-1 agonists have therapeutic potential as congeners with insulin in C-peptide-negative type 1 diabetes.

Characterization of dendritic cells in humans with type 1 diabetes.

The characterization of dendritic cells (DCs) in diabetes has primarily examined in vitro-generated DCs. In this study, we have compared the composition and phenotype of naturally occurring DCs within the peripheral blood of subjects with type 1 diabetes, latent-onset autoimmune diabetes in adults, and nondiabetic controls. We find that circulatory DC subsets exist in normal frequencies and phenotypic states in diabetic patients. In vivo, DCs were located around the pancreatic islets in type 1 diabetic patients, but were absent in pancreatic tissue of normal controls. These findings provide new insight toward understanding the pathological role of DCs in type 1 diabetes.

Glucagon-like peptide 1 improved glycemic control in type 1 diabetes.

BACKGROUND: Glucagon-like peptide-1 (GLP-1) and its agonists are under assessment in treatment of type 2 diabetes, by virtue of their antidiabetic actions, which include stimulation of insulin secretion, inhibition of glucagon release, and delay of gastric emptying. We examined the potential of GLP-1 to improve glycemic control in type 1 diabetes with no endogenous insulin secretion. METHODS: Dose-finding studies were carried out to establish mid range doses for delay of gastric emptying indicated by postponement of pancreatic polypeptide responses after meals. The selected dose of 0.63 micrograms/kg GLP-1 was administered before breakfast and lunch in 8-hour studies in hospital to establish the efficacy and safety of GLP-1. In outside-hospital studies, GLP-1 or vehicle was self-administered double-blind before meals with usual insulin for five consecutive days by five males and three females with well-controlled C-peptide-negative type 1 diabetes. Capillary blood glucose values were self-monitored before meals, at 30 and 60 min after breakfast and supper, and at bedtime. Breakfast tests with GLP-1 were conducted on the day before and on the day after 5-day studies. Paired t-tests and ANOVA were used for statistical analysis. RESULTS: In 8-hour studies time-averaged incremental (delta) areas under the curves(AUC) for plasma glucose through 8 hours were decreased by GLP-1 compared to vehicle (3.2 PlusMinus; 0.9, mean PlusMinus; se, vs 5.4 PlusMinus; 0.8 mmol/l, p <.05), and for pancreatic polypeptide, an indicator of gastric emptying, through 30 min after meals (4.0 PlusMinus; 3.1 vs 37 PlusMinus; 9.6 pmol/l, p <.05) with no adverse effects. Incremental glucagon levels through 60 min after meals were depressed by GLP-1 compared to vehicle (-3.7 PlusMinus; 2.5 vs 3.1 PlusMinus; 1.9 ng/l, p <.04). In 5-day studies, AUC for capillary blood glucose levels were lower with GLP-1 than with vehicle (-0.64 PlusMinus; 0.33 vs 0.34 PlusMinus; 0.26 mmol/l, p <.05). No assisted episode of hypoglycaemia or change in insulin dosage occurred. Breakfast tests on the days immediately before and after 5-day trials showed no change in the effects of GLP-1. CONCLUSION: We have demonstrated that subcutaneous GLP-1 can improve glucose control in type 1 diabetes without adverse effects when self-administered before meals with usual insulin during established intensive insulin treatment programs.