The study objective was to determine if Ramadan fasting was safe in patients with type 2 diabetes mellitus (T2D), based upon a determination of the effect of fasting on a broad range of physiological and clinical parameters, including markers of glycemic control and blood pressure. The study was carried out in Ramadan 1422 (December 2001-January 2002) at the Diabetology Services, Hopital Ibn Sina, Rabat, Morocco. One hundred and twenty T2D Moroccan patients (62 women, 58 men), aged 48-60 yrs with well-controlled diabetes through diet and/or oral hypoglycemic drugs (OHD), received dietary instructions and readjustment of the timing of the dose of OHD (gliclazide modified release) according to the fasting/eating periods. Anthropometric indices and physiological parameters (blood pressure, lipid, hematological, and serum electrolyte profiles, as well as markers of glycemic control, nutrition, renal and hepatic function) were measured on the day before Ramadan and then on the 15(th) and 29(th) day of fasting and thereafter 15 days later. Statistical analysis was done by standard methods. Ramadan fasting had no major effect on energy intake, body weight, body mass index, blood pressure, and liver enzymes. Fasting and post-prandial glucose levels decreased, while insulin levels increased. Diabetes was well controlled, as indicated by HbA1c, fructosamine, C-peptide, HOMA-IR, and IGF-1 values. There were fluctuations in some lipid and hematological parameters, creatinine, urea, uric acid, total protein, bilirubin, and electrolytes; however, all values stayed within the proper physiological range. In conclusion, diabetes was well-controlled in patients with dietary/medical management, without serious complications. With a regimen adjustment of OHD, diet control, and physical activity, most patients with T2D whose diabetes was well-controlled before Ramadan can safely observe Ramadan fasting.