The Magnitude of Weight Loss Induced by Metformin is Independently Associated with BMI at Baseline in Newly Diagnosed Type 2 Diabetes: Post-hoc Analysis from Data of a Phase IV Open-labeled Trial

BACKGROUND The impact of metformin on body weight is variable in T2DM patients among studies. The reasons for the discrepancies are still unknown. OBJECTIVES We aimed to find out the possible predictive factors of weight change induced by metformin based on an analysis of a phase IV open-labeled trial. MATERIAL AND METHODS We performed a sub-analysis from a prospective, multi-center phase IV open-labeled study in which 371 Chinese newly-diagnosed type 2 diabetes patients received 16 weeks' extended-release metformin monotherapy. The clinical characteristics including weight and laboratory assessments of subjects were collected every 4 weeks. The weight changes from baseline to week 4, 8, 12 and 16 were calculated respectively. The patients were divided into 4 groups by quartile statistics method according to magnitudes of weight change. RESULTS Of 371 enrolled patients, 324 patients had the weight records from baseline to week 16. The weight decreased gradually with each visit (p < 0.001) and the average weight loss was 2 kg after 16 weeks' treatment of metformin. The patients with higher BMI and bigger waist circumference at baseline showed a more pronounced weight loss. However, the magnitudes of weight loss were independently associated with BMI at baseline only. CONCLUSIONS Metformin can lead to weight loss gradually in newly-diagnosed type 2 diabetes patients. The magnitude of weight loss was independently and only associated with baseline BMI.