Aims: To compare the efficacy and safety of acarbose and metformin when added to sulphonylurea therapy in diabetic patients insufficiently controlled with sulphonylureas alone.
Methods: A 12-week, single-centre, placebo-controlled study, with 89 patients randomized to receive acarbose (100 mg t.d.s.), metformin (850 mg b.d.) or placebo in addition to their sulphonylurea therapy. The study was double-blinded with respect to acarbose/placebo and single-blinded for metformin/ acarbose and metformin/placebo. Patients started a strict dietary regimen 1 week before receiving their first dose of acarbose, metformin or placebo. This regimen was individually adjusted to metabolic status and energy requirements.
Results: The primary endpoint, HbA1c, decreased from baseline in all three groups after 12 weeks. The decrease was greater in the two groups receiving active therapy compared with placebo (acarbose -2.3+/-0.32%; metformin -2.5+/-0.16%; placebo -1.3+/-0.34%). There was no significant difference between acarbose and metformin (P=0.65). Differences between both active therapies and placebo were statistically significant (acarbose P < or = 0.01; metformin P < or = 0.004). Reductions in body weight over the treatment period were seen in all three groups and were greatest in the acarbose group (median weight reduction: acarbose 3.5 kg; metformin, 1.0 kg; placebo 1.4 kg). There were no significant differences in the incidence of gastrointestinal side-effects between the three groups and all regimens were generally well tolerated.
Conclusion: The results of the study demonstrate the equivalence of acarbose and metformin for improving metabolic control in patients insufficiently controlled with diet and sulphonylureas.