Introduction:
The aim of the study was to evaluate the influence of age and gender on the prevalence of overweight and obesity, body composition and fatty tissue distribution in young adults with type 1 diabetes.

Material and Methods:
197 patients with type 1 diabetes aged 20–40 years participated in the study. The control group consisted of 138 healthy adults. Body weight, height, waist and hip circumferences were measured. Analysis of body mass composition was performed using the bioimpedance. Study groups were stratified into cohorts aged < 30 and 30+ years.

Results:
Overweight and obesity were diagnosed in 35.5% and 13.2% of diabetic patients and in 26.1% and 7.3% of the control group, respectively (p=0.016). In the whole study group, advanced age (OR=1.10; p < 0.001) and diabetes mellitus (OR=2.25; p=0.001) predisposed patients to excess body weight. Women had a lower prevalence of overweight and obesity, but a trend toward excessive body mass was observed in diabetic females (OR=1.18; p=0.181). Diabetic females more often had abdominal obesity than control females (mean difference – 19.2%; p=0.020). Higher total body fat mass was found in the diabetic group (p=0.037). Diabetic females had a higher amount of absolute (p<0.001) and relative body fat mass (p=0.002), fat free mass (p=0.007), relative arm (p=0.007), leg (0<0.001) and trunk (p-=0.006) fat mass than control females. Diabetic males showed only higher relative fat mass of the lower limbs compared to control males (p=0.018).

Conclusions:
Patients with type 1 diabetes develop overweight and obesity in early adulthood more frequently than the general population and are characterized by higher body fat mass. Gender-related differences in body weight and composition in young type 1 diabetic adults were found.