Sex-related differences in the long-term risk of microvascular complications by age at onset of type 1 diabetes.

AIMS/HYPOTHESIS: This study examined sex-related differences in the cumulative risk of proliferative retinopathy (PR) and end-stage renal disease (ESRD) over 40 years of duration of type 1 diabetes according to age at diabetes onset.

METHODS: We assessed 4,416 patients from the Finnish Diabetic Nephropathy Study population. Kaplan-Meier analysis was used to provide cumulative incidence rates and Cox regression analyses for HRs.

RESULTS: There were no sex-related differences in the cumulative incidence of ESRD in patients diagnosed with type 1 diabetes between 0 to 4 and 5 to 9 years. Thereafter the risk started to diverge. The cumulative incidence of ESRD in patients diagnosed between 10 to 14 and ≥15 years was 17.4% (95% CI 13.4-21.2) and 13.0% (9.6-16.2) respectively in women, while in men it was 32.2% (28.0-36.1) and 24.6% (20.8-28.1) respectively. The respective HRs were (onset at 10 to 14 years) 1.9 (p < 0.0001) and (onset at ≥15 years) 1.8 (p < 0.001), respectively. There was no difference in the risk of PR between men and women diagnosed between 0 and 4 years of age, but progressive sex-related differences in the cumulative incidence of PR were observed with increasing age at onset. The HRs for men in the age-at-onset groups 5 to 9, 10 to 14 and ≥15 years of age were 1.3 (95% CI 1.0-1.6), 1.3 (1.1-1.6) and 2.1 (1.6-2.6) compared with women in these groups, respectively.

CONCLUSIONS/INTERPRETATION: The difference between the sexes with regard to risk of diabetic microvascular complications is highly dependent on the age at onset of diabetes. The risk of ESRD and PR risk doubled in men compared with women when age at onset was ≥15 years.