Although diabetics may be exempted from Ramadan fasting, many patients still insist on this worship. Aim of the present study is to compare the effects of glimepiride, repaglinide, and insulin glargine in type 2 diabetics during Ramadan fasting on the glucose metabolism. Patients, who were willing to fast, were treated with glimepiride (n = 21), repaglinide (n = 18), and insulin glargine (n = 10). Sixteen non-fasting control type 2 diabetics matched for age, sex, and body mass index were also included. Fasting blood glucose (FBG), post-prandial blood glucose (PBG), HbA1c, and fructosamine as well as lipid metabolism were evaluated in pre-Ramadan, post-Ramadan, and I-month post-Ramadan time points. There was no significant change from pre-Ramadan in FBG, PBG, and HbA1c variables in fasting diabetics at post-Ramadan and 1-month post-Ramadan. However, PBG was found higher in non-fasting control diabetics at post-Ramadan and 1-month post-Ramadan (p < 0.05 and p < 0.001, respectively). In fructosamine levels, a significant increase was noted both in fasting group and non-fasting group at 1-month post-Ramadan (p < 0.01 for all). However, no significant difference was found in the comparison of the changes in fructosamine levels between fasting group and non-fasting group. Risk of hypoglycemia did not significantly differ between fasting and non-fasting diabetics. There was no significant difference between three drug therapies regarding glucose metabolism and rate of hypoglycemia. No adverse effects on plasma lipids were noted in fasting diabetics. In this fasting sample of patients with type 2 diabetes, glimepiride, repaglinide, and insulin glargine did not produce significant changes in glucose and lipid parameters. (c) 2006 Elsevier Ireland Ltd. All rights reserved.