Effect Of Adjunct Metformin Treatment in Type 1 Patients

Adjunct metformin treatment was associated with sustained reductions of insulin dose and body weight for Type 1’s.

Despite intensive insulin treatment, many patients with type-1 diabetes (T1DM) have longstanding inadequate glycemic control.

Metformin is an oral hypoglycemic agent that improves insulin action in patients with type-2 diabetes. The study investigated the effect of a one-year treatment with metformin versus placebo in patients with T1DM and persistent poor glycemic control.

One hundred patients with T1DM, preserved hypoglycemic awareness and HemoglobinA(1c) > or = 8.5% during the year before enrolment entered a one-month run-in on placebo treatment. Thereafter, patients were randomized (baseline) to treatment with either metformin (1 g twice daily) or placebo for 12 months (double-masked).

Patients continued ongoing insulin therapy and their usual outpatient clinical care. The primary outcome measure was change in HbA(1c) after one year of treatment. At enrolment, mean (standard deviation) HbA(1c) was 9.48% (0.99) for the metformin group (n = 49) and 9.60% (0.86) for the placebo group (n = 51). Mean (95% confidence interval) baseline-adjusted differences after 12 months with metformin (n = 48) versus placebo (n = 50) were: HbA(1c), 0.13% (-0.19; 0.44), p = 0.422; Total daily insulin dose, -5.7 U/day (-8.6; -2.9), p<0.001; body weight, -1.74 kg (-3.32; -0.17), p = 0.030.
Minor and overall major hypoglycemia was not significantly different between treatments. Treatments were well tolerated.

From the results it was concluded that in patients with poorly controlled T1DM, adjunct metformin therapy did not provide any improvement of glycemic control after one year. Nevertheless, adjunct metformin treatment was associated with sustained reductions of insulin dose and body weight.

PLoS ONE. 2008;3(10):e3363. Epub 2008 Oct 9.