Patients with Type 1 diabetes (T1D) are normally exempt from the Ramadan fast; however, some patients insist on following the fast, often without the approval of their physicians. The aim of this study is to provide patients with T1D, who insist on fasting, with the most appropriate insulin regimen during the month of Ramadan. Seventeen patients with T1D who insisted on fasting were studied. Prior to Ramadan, the intermediate insulin was changed to ultralente in all patients. The total dose of insulin given to fasting patients by the end of Ramadan (45.7 +/- 14.4 U/day) was less than the total dose of insulin given before fasting (52.8 +/- 13.1 U/day) p<0.05. The ultralente and regular insulin constituted 70 and 30%, respectively, of the total insulin dose by the end of Ramadan, divided equally between Suhur (before sunrise) and Iftar (after sunset). There was no change in the glycosylated hemoglobin before and after fasting. Patients were instructed to break their fast after any episode of hypoglycemia. There were no severe daytime hypoglycemia episodes. We recommend that patients with T1D wishing to fast be switched to long acting insulin such as ultralente. The total insulin dose should consist of around 85% of their initial insulin dose and it should be composed of around 70% ultralente and 30% rapid insulin, divided equally between Suhur and Iftar.