Sex differences in incidence of IDDM in age-group 15-29 yr. Higher risk in males in Province of Turin, Italy

Abstract

Objective: To report the incidence of IDDM in the age-group 0-29 yr in the Province of Turin, Italy (951, 445 inhabitants 0-29 yr of age), over a 5-yr period (1984-1988) according to age, sex, and geographical region within the area and to identify any temporal trend.

Research design and methods: The survey used as the primary data source the list of all patients attending diabetic clinics, and as secondary data source, used the list of hospital discharges for diabetes.

Results: We identified 298 incident cases of IDDM in people 0-29 yr of age. Estimated completeness of ascertainment of the registry was 97%. Age-adjusted (world-standard) incidence rates were 7.40/100,000 (95% CI 6.28-8.71), 5.83 (4.95-6.86), and 6.70 (5.97-7.51), respectively, in the age-groups 0-14, 15-29, and 0-29 yr. Incidence was significantly higher in males than in females in the age-group 15-29 yr (7.36, 6.02-8.98, vs. 4.21, 3.12-5.56). An increasing incidence from rural areas to the greater Turin area (city and its industrial belt) was evident. No significant temporal trend during the study period was found, although year-to-year variability was evident, with the highest incidence in 1984.

Conclusions: This study suggests a high male-to-female ratio of incidence of IDDM after 14 yr; either sex hormones or different exposure to environmental determinants could be involved.