Efficacy of metformin on postprandial plasma triglyceride concentration by administration timing in patients with type 2 diabetes mellitus: A randomized cross‐over pilot study

AIMS/INTRODUCTION: Preprandial metformin administration significantly reduces postprandial plasma triglyceride levels in animal studies by reducing intestinal absorption through delayed gastric emptying. However, this effect has not been shown in a clinical study. Therefore, we planned to investigate the efficacy of preprandial metformin administration on postprandial hypertriglyceridemia and the related gastrointestinal effects in patients with type 2 diabetes mellitus. MATERIALS AND METHODS: A total of 11 patients taking single‐dose metformin at 500–1,000 mg, with non‐fasting plasma triglyceride levels of 150–1,000 mg/dL, were recruited at a single university hospital. The difference between preprandial and postprandial metformin administration on postprandial hypertriglyceridemia was examined by a meal test. The gastrointestinal effects of metformin, including stomach heaviness, heartburn and satiety, were also assessed using a visual analog scale. RESULTS: The mean bodyweight of patients was 80.6 kg (body mass index 27.9 kg/m(2)), and the mean non‐fasting plasma triglyceride level was 275.9 ± 57.0 mg/dL. The area under the curve of triglyceride during the meal test was significantly lower in the preprandial protocol than in the postprandial protocol (P < 0.05). Compared with postprandial administration, preprandial administration of metformin increased satiety (P = 0.036) without stomach heaviness or heartburn. CONCLUSIONS: Preprandial metformin administration significantly reduced plasma triglyceride level during meal testing without marked exacerbation of gastrointestinal adverse effects. The present results suggest that a simple change in the timing of metformin administration represents a novel approach for enhancing triglyceride‐lowering strategies in patients with type 2 diabetes mellitus and postprandial hypertriglyceridemia.