In 9 years (1990-1998), 40 Arab patients between the ages of 0 and 18 years had newly diagnosed diabetes mellitus (DM) at the Al-Ain hospital, United Arab Emirates (UAE). In this cohort, 35 patients had Type 1 DM while the remaining five patients had features of early onset Type 2 DM. For Type 1 DM patients, the mean age at diagnosis of was 9.2+/-4.1 years. At presentation, their mean plasma glucose was 27.6+/-11/mmol with 28 (80%) patients having diabetic ketoacidosis (DKA), both being much higher than generally reported in the West. The mean insulin requirement increased from 0.84+/-0.27 U/kg per 24 h (0-9-year group) to 1.02+/-0.33 U/kg per 24 h (10-18-year group), P=0.055. The home glucose monitoring and the glycaemic control of these Type 1 DM patients were sub-optimal with 28% of patients having recurrence of DKA. Among the Type 2 DM patients, four (80%) were obese with a positive family history of Type 2 DM. All of them initially responded to diet and oral hypoglycaemic drugs. Public education about DM in childhood and prevention of adolescent obesity remain major public health challenges in the UAE.