Objectives: Obesity and hypertension are associated with an adverse metabolic profile and systemic low-grade inflammation. Metformin reduces weight and inflammation in patients with diabetes, but it is unclear whether it has beneficial effects in patients without diabetes. The objective was to explore whether metformin-based treatment could benefit obesity-related hypertension without diabetes.
Methods: A randomized, double-blind, placebo-controlled factorial trial was conducted in 360 obese hypertensive patients without diabetes in Chongqing, China. After a 1-2-week run-in period, patients were randomly assigned to metformin (500 mg once per day) or placebo, as well as to an antihypertensive medication. Change in blood pressure, obesity measurements and metabolic profile were assessed at 24 weeks.
Results: The 180 participants randomized to metformin and 180 randomized to placebo were similar at baseline. At 24 weeks, metformin compared with placebo did not have significant effects on blood pressure, blood glucose, high-density or low-density lipoprotein cholesterol, but it did reduce total serum cholesterol (0.2 mmol/l, P = 0.038). Metformin also significantly reduced weight (-0.7 kg, P = 0.006), BMI (-0.2 kg/m, P = 0.024), waist circumference (-0.9 cm, P = 0.008), and both subcutaneous (-6.1 cm, P = 0.043) and visceral adiposity (-5.4 cm, P = 0.028) as measured by computed tomography, and lowered serum high-sensitivity C-reactive protein levels (-0.6 mg/dl, P < 0.001). There was no significant difference in adverse events (P = 0.785).
Conclusions: Metformin has no effect on blood pressure and blood glucose levels, but it does reduce total cholesterol, abdominal obesity and C-reactive protein levels in obese hypertensive patients without diabetes.