SAN DIEGO – Girls with type 1 diabetes had significantly increased mean hemoglobin A1c levels, body mass index, LDL cholesterol, and C-reactive protein, compared with boys who have the disease, results from a single-center study demonstrated.
The finding suggests that adolescence "may be a critical period for CVD prevention in girls with type 1 diabetes," Talia L. Brown said at the annual scientific sessions of the American Diabetes Association. "Future studies should investigate factors contributing to these gender differences."
Adults with type 1 diabetes are known to have a higher risk of cardiovascular disease compared with nondiabetic adults, said Ms. Brown, a graduate student who is a research assistant at the Barbara Davis Center for Childhood Diabetes, Aurora, Colo.
"There is a greater relative increase in women, where women with type 1 diabetes have four times the CVD risk as nondiabetic women," Ms. Brown said. "Meanwhile, men with type 1 diabetes have two times greater CVD risk than nondiabetic men. It is uncertain when these gender differences begin."
To find out, she and her associates compared the CVD risk profile of 302 adolescents with type 1 diabetes with 100 nondiabetic adolescents and evaluated gender differences between the groups. The adolescents’ mean age was 15 years. Tanner stage was assessed by a physician or self report at the visit. Measures included fasting lipids, assays for HbA1c and C-reactive protein, diastolic and systolic blood pressure, and body mass index z score. The researchers used questionnaires to assess physical activity and average insulin dose, and multivariate linear regression to examine each CVD risk factor.
Ms. Brown reported that physical activity was equivalent among the study participants (a mean of about 2 hours per day), and insulin dose was similar between boys and girls (a mean of 1.1 vs. 1.2 units/kg, respectively).
Compared with boys with type 1 diabetes, girls with the disease had significantly increased mean hemoglobin A1c (9.1% vs. 8.7%, respectively), BMI z score (0.72 vs. 0.49), LDL cholesterol (95 mg/dL vs. 82 mg/dL), and CRP (0.86 mg/dL vs. 0.15 mg/dL). Boys with type 1 had higher levels of systolic blood pressure, compared with girls with the disease – 115 mm Hg vs. 111 mm Hg, respectively. But girls with type 1 had higher levels of systolic blood pressure, compared with nondiabetic girls (111 mm Hg vs. 106 mm Hg, respectively).
"Girls with diabetes had higher LDL levels than both boys with type 1 diabetes and girls without diabetes," Ms. Brown added. "CRP was ninefold higher in girls with type 1 diabetes than in both girls without diabetes and boys with type 1 diabetes."
After adjustment for HbA1c and BMI z score, a significant increase in CRP and LDL in girls with type 1 diabetes remained. The researchers also found a significant interaction between gender and diabetes, "causing type 1 diabetes to have a more detrimental effect in girls than in boys with regard to LDL cholesterol and systolic blood pressure," Ms. Brown said.
Increased HbA1c and body mass index "are likely to contribute to the increased blood pressure, inflammation, and cholesterol that we observed in girls with type 1 diabetes," she said. "These findings are somewhat unexpected, because generally there can be an inverse relationship between glycemic control and weight. Increased HbA1c and obesity are likely to translate into worse CVD outcomes for females, and raises concern for the long-term effects in CVD health."
When asked to speculate why HbA1c and body mass index were increased in girls with type 1, Ms. Brown said that girls generally "have a hard time controlling both [factors], so it’s hard to know what’s contributing to this."
Prevention efforts such as maintaining a healthy diet, getting adequate physical exercise, and controlling blood pressure and cholesterol levels "may improve this problem," she said.
The study was funded by the Juvenile Diabetes Research Foundation, the National Institute of Diabetes and Digestive and Kidney Diseases, and Children’s Hospital Colorado Clinical Translational Research Center.
Ms. Brown said that she had no relevant financial conflicts to disclose.