A comparison of treatment with metformin and gliclazide in patients with non-insulin-dependent diabetes.

Twenty-seven obese non-insulin-dependent diabetic patients, treated with dietary carbohydrate restriction and metformin, were recruited from the diabetic outpatient clinic and entered into an open crossover study with gliclazide. Twenty-one patients completed the study. During three months observation on metformin, the mean weight of the group fell by 1.0 kg with 14 patients losing a mean of 1.8 kg with 14 patients losing a mean of 1.8 kg, 3 remaining unchanged and 4 gaining a mean weight of 1.1 kg. Over the subsequent three months on gliclazide, the mean weight of the group rose by 1.4 kg with 16 patients gaining a mean of 2.2 kg, two remaining unchanged and 3 losing a mean of 2.0 kg. In addition, 10 patients were heavier after gliclazide than at the time of recruitment (mean 2.6 kg), 3 were unchanged and 8 had lost weight since commencing the trial (mean 2.1 kg), mostly due to greater loss on metformin than gain on gliclazide. Glycaemic control did not improve significantly during the observed period on metformin but lower concentrations of fasting glucose and total glycosylated haemoglobin were achieved with gliclazide. Mean plasma insulin concentration was significantly higher and mean serum lactate was significantly lower during treatment with gliclazide. In conclusion, gliclazide does not support weight loss in obese non-insulin-dependent diabetic patients to the same extent as metformin but the difference between the two drugs is small. Gliclazide is a suitable oral hypoglycaemic agent for use in the obese diabetic who cannot be controlled by diet alone.