Aim: To evaluate the effect of linagliptin vs. metformin on insulin secretion, insulin sensitivity and glucose control in patients with impaired glucose tolerance (IGT).
Patients and methods: A randomized, double-blind, clinical trial with parallel groups was performed in 16 adults with IGT. Lipid profile and A1C were evaluated prior to and after the intervention. Glucose and insulin were measured at 0, 30, 60, 90 and 120 min after a 75-g oral dextrose load. Eight patients received metformin (500 mg) twice a day before meals for 3 months. The remaining eight patients received placebo (500 mg) in the morning and linagliptin (5 mg) in the evening before meals. Area under the curve (AUC) of glucose and insulin, total insulin secretion, first-phase of insulin secretion, and insulin sensitivity were assessed.
Results: after linagliptin administration, a significant decrease in glucose at 90 min (10.8 ± 2.6 vs. 7.9 ± 2.2 mmol/L; p <0.05), 120 min (8.8 ± 0.9 mmol/L; p <0.05) and AUC of glucose (1168 ± 210 vs. 953 ± 207 mmol/l; p <0.05) were observed. Metformin administration decreased insulin significantly at 0 min (94.8 ± 25.8 vs. 73.8 ± 24.6 pmol/L; p <0.05).
Conclusion: 3-month administration of linagliptin in patients with IGT decreased glucose at 90 and 120 min after a 75-g oral dextrose load and AUC of glucose. Metformin decreased insulin at 0 min.