Trends and predictors of blood pressure among children and adults during the first 10 years of type 1 diabetes

Purpose Type 1 diabetes is a known risk factor for hypertension; however, there are no population-based longitudinal data on blood pressure during the first 10 years of diabetes. A Wisconsin population-based incident cohort with type 1 diabetes was followed for up to 10 years from 1987 to 2001 to examine (i) whether blood pressure levels are increased in diabetes compared with individuals of similar age in the general population and (ii) whether diabetes duration and glycosylated hemoglobin (GHb) levels are associated with elevated blood pressure in early diabetes. Methods Systolic and diastolic blood pressure (outcome), and demographic, medical, and anthropomorphic data were collected with physical exams (conducted at 4–6 months and at 4, 7, and 9 years duration), phone questionnaires at enrollment, and semiannual self-administered questionnaires. Age at diagnosis (exposure) was determined from medical records. Total GHb (exposure) was determined from blood samples collected up to three times each year. Multivariable random-effects regression modeling was used for the analysis. Results Data were available on 525 individuals (1326 observations), ranging in age from 1 to 40 years. Mean systolic and diastolic blood pressures were similar across the age range in individuals with diabetes and the general population sample from the Second National Health and Nutrition Examination Survey (NHANES II). Regression analysis showed that diastolic blood pressure increased with duration for all age groups except young adults, and systolic blood pressure increased with duration in the youngest age group. GHb was not related to blood pressure. Conclusion These data suggest that differences in blood pressure between individuals with and without type 1 diabetes are small during the first 10 years of disease; however, the increase in blood pressure with duration may be an early indicator of the effect of diabetes on blood pressure.