There are concerns as to the effect of the ramadan on kidney function in patients with type 2 diabetes who choose to fast, especially when ramadan occurs during a hot, dry season with a long period of daylight hours. This study objective is to explore the safety of fasting for the whole month of ramadan on renal physiology among patients with type 2 diabetes. We followed diabetic type 2 patients with stable kidney function who chose to fast during the month of ramadan. Body mass index (bmi), blood pressure (bp),serum creatinine with calcul of glomerular filtration rate(gfr) was recorded before the beginning and at the end of the month. Total body water was measured with an impedancemeter before and after ramadan. Only 39 patients who were able to fast 4 weeks and responded to the proposed follow-up after ramadan. Mean baseline estimated bmi, bp,gfr and total body water were respectively; 30,25kg/m2, 13/7mmhg,130 ml/min, 34,69 %. A rise of serum creatinine was noted during fasting by the end of ramadan in 23 patients(57%)and glomerular filtration rate had concomitantly decreased. We noticed that total body water has decreased in 7 patients (18 %). The risk of developing dehydration and acute renal failure was significantly higher for patients with baseline creatinine clearance of <60 ml/min/1.73 m 2 and a total body water under the average. The small sample size does not allow us to draw any firm conclusions on fasting during ramadan in well controlled diabetic type 2 patients. Studies on larger numbers of patients are required.