Brief Summary:
The present study is a phase I, single-centre, double-blind, randomized, cross-over (3 treatments, 3 treatment periods and 6 sequences), stratified (background medication: metformin vs. diet-only), placebo-controlled study, comparing periods lasting 6-9 days on treatment with repeated doses of vildagliptin, sitagliptin, or placebo, with wash-out periods between treatment periods lasting 21 days minimum.
The study was designed to directly compare the effects of vildagliptin and sitagliptin on incretin hormone responses, glycaemia, and insulin as well as glucagon secretory responses in patients with type 2 diabetes.
Detailed Description:
Design. The present study is a phase I, single-centre, double-blind, randomized, cross-over (3 treatments, 3 treatment periods and 6 sequences), stratified (background medication: metformin vs. diet-only), placebo-controlled study, comparing periods lasting 6-9 days on treatment with repeated doses of vildagliptin, sitagliptin, or placebo, with wash-out periods between treatment periods lasting 21 days minimum.
Experimental procedures. Meal tests were performed in the morning after an overnight fast. The standardized mixed meal was composed of 2 eggs (100 g), 1 slice (50 g) of whole grain rye bread, 1 slice (50 g) of rye flour bread, 10 g of fat-reduced margarine, 20 g of boiled ham, and 25 g of diet jam, amounting to 450 kcal, 50 % carbohydrate, 20 % protein, and 30 % fat (based on calorie count). Patients were allowed to drink tea (black or fruit-based) or de-caffeinated coffee ad libitum.
Blood sampling. Plasma glucose was determined in capillary samples taken from hyperaemic ear lobes. Venous blood was collected from indwelling venous cannulas placed in a distal forearm vein, for the determination of insulin, C-peptide, glucagon, GLP-1 (total), GLP-1 (intact), glucose-dependent insulinotropic polypeptide (GIP) (total), GIP (intact), and free fatty acids. After drawing basal blood specimens at -15 and 0 min, blood was taken at 15, 30, 45, 60, 90, 120, 180, and 240 min.
Laboratory determinations. Glucose, insulin, C-peptide, total GLP-1 (C-terminally directed assay), intact GLP-1 (sandwich ELISA), total GIP (C-terminally directed assay), intact GIP (N-terminally directed assay) and glucagon were determined.