BackgroundWe aimed to determine the prevalence of overweight and obesity among children, adolescents and young adults with type 1 diabetes mellitus (T1DM), and to assess the prevalence of the metabolic syndrome and its components. MethodsThe study cohort comprised 326 (168 women) consecutive patients aged 5 to 30years diagnosed with T1DM and followed up in the Juvenile Diabetes Clinic, Maccabi Health Care Services. Anthropometric measurements, blood pressure, presence of additional diseases, other medications, HbA(1c), triglycerides and high density lipoprotein cholesterol levels were obtained. ResultsThe mean age in the study group was 18.56.0years, and the mean diabetes duration was 8.7 +/- 5.0years. Mean HbA(1c) level was 8.1 +/- 1.3%. Nineteen per cent of the study population was overweight (85th>body mass index<95th percentile) and 5.2% was obese (body mass index95th percentile). Female patients aged 1518 and 1825years were significantly overweight compared with healthy Israeli women in the same age groups, 33.3% versus 12.7% and 26.3% versus 7.8%, respectively, p<0001. There were no obese female patients in the 1518 age group. Among the men in all age groups, there was no difference in the prevalence of overweight and obesity compared with healthy men in the general population. There was no difference in the age of onset, disease duration, HbA(1c) levels, treatment with anti-depressants and associated morbidities between the normal weight, overweight and obese groups. Obese patients had lower levels of HDL and increased prevalence of hypertension and metabolic syndrome. ConclusionsOverweight but not obesity was more prevalent in women with T1DM. Metabolic syndrome and its components were more prevalent among overweight and obese individuals with T1DM than among normal weight individuals. Copyright (c) 2014 John Wiley & Sons, Ltd.