Increased risk of diabetes among relatives of female insulin‐treated patients diagnosed at 15–34 years of age

Abstract

This study aimed to determine the risk of developing diabetes among relatives of patients diagnosed between 15 and 34 years of age who were treated with insulin. Our second aim was to determine whether there was a difference in risk of diabetes between relatives of male and female patients. A questionnaire was sent to patients in the Diabetes Incidence Study in Sweden registry diagnosed between 1983 and 1993 to determine the presence of first-degree relatives with diabetes. In 3087 index patients treated with insulin, 17.8% (95% confidence interval 16.5, 19.2) had a first-degree relative (excluding offspring) treated with insulin, the frequency being higher in female (19.8%) than in male (16.5%, P = 0.018) patients. A total of 10.7% had a parent treated with insulin. The prevalence of insulin-treated diabetes was higher among parents of female (12.5%) than of male (9.5%), insulin-treated index patients (P = 0.0068). A similar difference was observed using life table analysis (P = 0.0025), which also showed that the risk by 63 years of age was 7.6% for parents of female and 4.9% for parents of male insulin-treated index patients. In insulin-treated index patients, 8.4% had a sibling with insulin-treated diabetes. We conclude that the risk for relatives of women with insulin-treated diabetes was higher than for relatives of insulin-treated male patients. We suggest that greater genetic susceptibility is required for females compared with males in the 15-34 age group in order to develop diabetes and hence females might carry more diabetes genes since more of their relatives also develop diabetes.