[Effectiveness of treatment with metformin in patients with type 2 diabetes mellitus poorly controlled with insulin treatment]. Metformin as additional therapy in adolescents with poorly controlled type 1 diabetes: randomised placebo-controlled trial with aspects on insulin sensitivity.
Combined treatment with insulin plus metformin could be a good alternative to improve the glycemic control in patients with type 2 diabetes mellitus poorly controlled with insulin therapy. We retrospectively studied 21 obese insulin-treated type 2 diabetic patients with deficient metabolic control (HbA1c 9.2 +/- 1.2%) who were treated with metformin for a minimum of 8 months. After 4 months of treatment, a significant decrease in the percentage of HbA1c was observed (delta HbA1c -1.07 +/- 1.12%; p < 0.01), with maintained values since then. Non changes in body weight or insulin requirement were noted. Our results suggest that the addition of metformin to insulin treatment is a safe and effective strategy for the improvement of glycemic control among obese type 2 diabetic patients. Metabolic control often deteriorates during puberty in children with type 1 diabetes. The aim of the present study was to investigate whether addition of metformin for 3 Months improves metabolic control and insulin sensitivity.
                Twenty-six of 30 randomised adolescents with type 1 diabetes (18 females, eight males) completed a double-blind placebo-controlled trial. Their mean age was 16.9+/-1.6 (s.d.) Years, mean glycated haemoglobin (HbA(1c)) 9.5+/-1.1% and daily insulin dosage 1.2+/-0.3 U/kg. The participants were randomised to receive oral metformin or placebo for 3 Months. HbA(1c) was measured Monthly, and peripheral insulin sensitivity was assessed by a euglycaemic hyperinsulinaemic clamp at baseline and at the end of the study.
                HbA(1c) decreased significantly in the group treated with metformin, from 9.6 to 8.7% (P<0.05), but was unchanged in the placebo group (9.5 vs 9.2%). Peripheral glucose uptake divided by mean plasma insulin concentration was increased in the metformin group (P<0.05) but not in the placebo group. Initial insulin sensitivity was inversely correlated to changes in HbA(1c) (r=-0.62; P<0.05) and positively correlated to changes in insulin sensitivity (r=0.77; P<0.01).
                In this double-blind placebo-controlled study we found that metformin improves metabolic control in adolescents with type 1 diabetes. The effect seems to be associated with an increased insulin-induced glucose uptake.
There is some evidence suggesting improvement of metabolic control in poorly controlled adolescents with type 1 diabetes, on addition of metformin to insulin therapy. Stronger evidence is required from larger studies, carried out over longer time periods to document the long-term effects on metabolic control, health-related quality of life as well as morbidity and mortality in those patients.