Effectiveness of metformin and lifestyle interventions as an initial treatment in Japanese patients with newly diagnosed type 2 diabetes: a prospective observational study.

Although global guidelines recommend metformin and lifestyle interventions as an initial treatment in patients with newly diagnosed type 2 diabetes (T2DM), few reports exist about its effectiveness in Japanese patients. To examine its effectiveness, we performed a prospective observational study within a routine clinical setting. We provided metformin (≥1,500 mg/day) and lifestyle interventions to 23 patients with newly diagnosed T2DM (20 men and 3 women, mean age 53 years, mean body mass index [BMI] 25.7 kg/m(2)). After 16 weeks, HbA1c levels significantly decreased from 9.1±2.1% (mean±SD) to 6.6±0.8% (p<0.001). Thirteen patients (56.5%) achieved a target HbA1c<6.5%. We did not find a significant correlation between baseline BMI and the changes in HbA1c (ΔHbA1c) (r=-0.165, p=0.451). In contrast, we found a significant correlation between baseline fasting plasma glucose and ΔHbA1c (r=-0.755, p<0.001). Body weight decreased from 73.3±13.3 kg to 69.8±11.6 kg (p<0.001). Total cholesterol, low density lipoprotein - cholesterol, non-high density lipoprotein-cholesterol, and serum vitamin B-12 concentrations also significantly decreased. Adverse events included diarrhea (26.1%) and mild elevation of liver enzymes (8.7%). These results suggest that metformin and lifestyle interventions is effective and safe as an initial treatment in Japanese patients with newly diagnosed T2DM.