The effect of metformin on the incidence of type 2 diabetes mellitus and cardiovascular disease risk factors in overweight and obese subjects--the Carmos study.

UNLABELLED: We investigated whether the addition of metformin to the treatment of overweight and obese individuals further reduces the incidence of type 2 diabetes mellitus (T (2)DM), prediabetes and metabolic syndrome (MetS) and improves cardiovascular disease (CVD) risk factors (RFs). DESIGN AND METHODS: We studied 366 adults (mean age 53.0+/-0.5 SE years, and mean BMI 32.3+/-0.2 SE Kg/m (2)) without CVD. All subjects received lifestyle recommendations and drug management of CVD-RFs, whilst 95 of them were additionally given metformin. The follow-up period lasted 12 months.
RESULTS: At the end of the study the frequency of T (2)DM in the metformin and non-metformin group was 1.1 and 8.1%, respectively (risk difference=-7% with 95% CI from -12.7% to -1.4%, p=0.012). Participants with prediabetes displayed a greater reduction in the incidence of T (2)DM after taking metformin compared to those who had not received this drug (risk difference=-18.5% with 95%CI from -33.1% to -3.9%, p=0.010). Metformin had a similar beneficial impact on subjects with MetS (risk difference=-12.9% with 95% from -25% to -0.7%, p=0.040) and this was attributed to the greater increase in HDL-C (p=0.046) and decrease in fasting plasma glucose levels (p=0.024). Metformin also achieved a greater reduction in total cholesterol and LDL-C levels (metformin vs. non-metformin treated subjects: -31.9 vs. -17.3 mg/dl, p=0.001, and -26.2 vs. -15.9 mg/dl, p=0.006, respectively).
CONCLUSIONS: Metformin reduces the occurrence of T (2)DM in overweight and obese non-diabetic adults and decreases the rate of MetS by improving the CVD risk factor profile.