Glucagon-Like Peptide-1 Infusion Must Be Maintained for 24 h/day to Obtain Acceptable Glycemia in Type 2 Diabetic Patients Who Are Poorly Controlled on Sulphonylurea Treatment

OBJECTIVE: To assess the efficacy and safety of glucagon-like peptide-1 (GLP-1) on the plasma glucose level when given as a continuous infusion for either 16 or 24 h per day to type 2 diabetic patients who were poorly controlled on sulfonylurea treatment. RESEARCH DESIGN AND METHODS: This single-center, randomized, parallel, double-blind, placebo-controlled trial was conducted in 40 hospitalized patients who were randomized to receive infusions of either placebo or GLP-1 4 or 8 ng. kg(-1). min(-1) for either 16 or 24 h per day for 7 days. At predetermined intervals, 24-h profiles of glucose, glucagon, and insulin were measured. Adverse events and clinical chemistry and hematology were recorded. RESULTS: For all active treatment groups, the change in average glucose (area under the curve AUC for day 7 minus AUC for day 0 divided by 24 h) was statistically significantly different from placebo (P < or = 0.001). The GLP-1 8 ng. kg(-1). min(-1) dose given for 24 h was more efficacious than any of the other doses (P < or = 0.05). Nocturnal and fasting plasma glucose levels at day 7 were greater in the 16-h groups compared with the 24-h groups (P < or = 0.05). Insulin AUC did not show any treatment effect for any of the treatment groups when change was assessed from day 0 to day 7. However, for the 16-h groups, the pattern of the insulin profiles changed; the insulin profiles were considerably higher during the initial 3-4 h after restart of the GLP-1 infusion on day 7, although there was a tendency for insulin levels to decrease during the afternoon and evening. Glucagon AUC decreased significantly for all active treatment groups compared with placebo. GLP-1 was generally well tolerated. CONCLUSIONS: This study demonstrated that GLP-1 should be given continuously to obtain the most optimal glycemic control. Because of the short plasma half-life of native GLP-1, long-acting derivatives should be developed to make GLP-1 treatment clinically relevant.