The effect of metformin in overweight patients with type 1 diabetes and poor metabolic control

Metformin as adjunct to intensive insulin therapy may improve glucose metabolism and thereby prevent the development of cardiovascular risk factors in patients with type 1 diabetes. Double-blinded intervention with 2000 mg metformin or placebo daily in 24 type 1 diabetic patients as adjunct to intensive insulin therapy. Primary endpoint was HbA1c, while secondary endpoints were body weight, frequency of hypoglycaemia, blood pressure, lipids, insulin dosage and self-monitored blood glucose profiles were measured. After 24 weeks, no difference in HbA1c was seen between the metformin and placebo groups (-0.5 +/- 0.3 vs. -0.2 +/- 0.2%, P = 0.26. Delta mean +/- S.E.M). Mean diurnal blood glucose profiles showed no statistical significant difference between the groups. The total daily insulin dose (IU) was significantly reduced in the metformin group compared to placebo after 24 weeks (-5.9 +/- 2.2 vs. 2.9 +/- 1.7, P = 0.004. Delta mean +/- S.E.M). An increase in the frequency of hypoglycaemia was seen in the metformin group (0.7 +/- 0.9 vs. 0.3 +/- 0.5 events patient(-1) week(-1), P = 0.005), and a reduction in body weight was found using metformin compared to placebo (-3.0 +/- 1.0 vs. 0.8 +/- 1.1, P = 0.02. Delta mean +/- S.E.M). Lipids and blood pressure did not differ significantly after intervention. Metformin, as adjunct to intensive insulin therapy, was associated with a reduction in the total daily insulin dose and a significant weight loss in patients with type 1 diabetes mellitus.