INS and type 1 diabetes mellitus: Meng et al. evaluated the effect of metformin in 1183 subjects with type 1 diabetes, demonstrating that metformin was associated with reductions in BMI (−1.14, 95% CI −2.05 to −0.24, p = 0.01), insulin requirements (−0.47, 95% CI −0.70 to −0.23, p = 0.0001), total cholesterol (−0.23, 95% CI −0.34 to −0.12, p < 0.0001), and low-density lipoprotein cholesterol (−0.20, 95% CI −0.29 to −0.11, p < 0.0001) in type 1 diabetic patients.