30-days effects of vildagliptin on vascular function, plasma viscosity, inflammation, oxidative stress, and intestinal peptides on drug-naïve women with diabetes and obesity: a randomized head-to-head metformin-controlled study

BACKGROUND: Obesity is the main risk factor for diabetes and excessive visceral fat triggers low-grade inflammatory process, mediated by activation and release of cytokines and high flow of free fatty acids that contribute to insulin resistance, increased oxidative stress, and impaired endothelial function. Metformin and vildagliptin have known vasculoprotective actions, but the value of these drugs on drug-naïve diabetic patients during 30 days use warrants investigation. Our purpose was to observe their effects on endothelial function, oxidative stress, inflammatory biomarkers, and plasma viscosity. METHODS: 38 women with obesity and type 2 diabetes drug-naïve, aged between 19 and 50 years, BMI ≥ 30 kg/m(2), were recruited and subjected to measurements of endothelial function, nutritive skin microvascular reactivity, plasma viscosity, inflammatory and oxidative stress biomarkers at baseline and randomized 1:1 to ingest metformin (850 mg twice/day) or vildagliptin (50 mg twice/day) during 30 days, and then, re-evaluated. RESULTS: No differences between groups were noticed at baseline. After treatment, vildagliptin promoted an improvement on endothelial-dependent and -independent vasodilatations, at arteriole level, while metformin resulted in improved nutritive microvascular reactivity, at the capillary level. Intragroup analysis showed that vildagliptin reduced insulin, C-peptide and oxidized LDL, and increased adiponectin and glucagon-like peptide-1 while metformin reduced weight, plasma glucose, total cholesterol, HDL-c, LDL-c, and dipeptidyl peptidase-4 activity, with an unexpected increase on tumor necrosis factor-α. No significant difference in plasma viscosity was noted. CONCLUSIONS: In the vascular beds investigated, both drugs used for only 30 days improved endothelial function, through distinct, and possibly, complementary mechanisms on drug-naïve diabetic women. Trial Registration ClinicalTrials.gov: NCT01827280