Study design

We carried out a randomized, open‐labeled, cross‐over pilot study to investigate the effects of metformin administration on postprandial hypertriglyceridemia in patients with type 2 diabetes mellitus (Figure 1a,b). The primary end‐point was the difference in the change in postprandial serum TG levels between preprandial (pre‐Met) and postprandial (post‐Met) metformin administration. Key secondary outcomes were changes in blood glucose, serum insulin and active glucagon‐like peptide‐1 (GLP‐1) concentrations. A visual analog scale (VAS) was used to assess gastrointestinal symptoms and satiety as secondary outcomes. This study was carried out in accordance with the principles of the Declaration of Helsinki. The research protocol was approved by the ethics committee of Shiga University of Medical Science on 22 March 2016. The study is registered with UMIN (UMIN000022699), and all participants gave written informed consent to participate.

(a) Study design. (b) Meal tests under the preprandial metformin administration (pre‐Met; 500–1,000‐mg single dose) and postprandial metformin administration (post‐Met) protocols were carried out alternately. The participants ingested a cookie consisting of 75 g carbohydrate (flour starch and maltose) and 28.5 g fat. Blood was collected at fasting (−30, 0), 60, 120, 180 and 240 min after ingestion of the cookie. GLP‐1, glucagon‐like peptide‐1.