Better weight control with metformin and insulin

In non-obese patients with type 2 diabetes, insulin plus metformin provides the same glycaemic control as insulin plus an insulin secretagogue and with less weight gain, new research finds. The randomised double blind trial examined 101 patients with long-term (approximately 10 years) diabetes for 12 months, of whom 52 were given metformin plus insulin and 49 were given repaglinide plus insulin. All patients also received biphasic insulin aspart 70/30 (30% soluble insulin aspart and 70% intermediate acting insulin aspart) 6 units once a day before dinner and insulin dose was adjusted aiming for a fasting plasma glucose concentration of 4.0-6.0 mmol/l. The study found that HbA1c concentration was reduced by a similar amount in the two treatment groups (insulin plus metformin: mean HbA1c 8.15% v 6.72%; insulin plus repaglinide: 8.07% v 6.90%), and total daily insulin dose and risk of hypoglycaemia and other adverse events were also similar. However, weight gain was less with metformin plus insulin than with repaglinide plus insulin (difference in mean body weight between treatments –2.51 kg). The study authors said that there is currently “an almost complete lack of evidence to guide treatment choices, including the use of metformin, for non-obese patients with type 2 diabetes”. “This study suggests that… the use of metformin or, in those patients who remain free of significant hypoglycaemia, an insulin secretagogue as an adjunct therapy to insulin might have beneficial effects on glycaemic control,” they said. BMJ 2009;339:b4324....