Risk of future microvascular and macrovascular disease in people with Type 1 diabetes of very long duration: A national study with 10-year follow-up

Aims: To describe factors associated with prevalence or absence of microvascular and macrovascular complications in people with Type 1 diabetes of very long duration and to investigate the risk factors associated with the incidence of such complications. Methods: We included individuals with Type 1 diabetes who had been entered in the Swedish National Diabetes Register between 2002 and 2004 (n = 18 450). First, risk factor distribution in people with diabetes duration of ≥ 50 years was compared between people with and without complications. Second, the incidence of complications during a 10-year follow-up period was studied in all individuals who had no complications at baseline. Results: Among people with a diabetes duration of ≥ 50 years (n = 1023), 453 (44%) had macrovascular disease, 534 (52%) had microvascular disease and 319 (31%) did not have either of the diagnoses. Factors that differed significantly between people with and without macrovascular disease were gender, age, HbA_1c, BMI, LDL cholesterol, HDL cholesterol, triglycerides, systolic blood pressure, albuminuria, antihypertensive medication and lipid-lowering medication. The same factors differed significantly between people with and without microvascular disease, with the exception of gender and HDL cholesterol. During the follow-up period, 6.1% of the study cohort were diagnosed with macrovascular disease and 19.6% with microvascular disease. Incidence of macrovascular disease was significantly associated with HbA_1c levels. Hazard ratios decreased with longer diabetes duration. Conclusions: People with Type 1 diabetes who have survived ≥ 50 years without complications are significantly younger, and have significantly lower HbA_1c levels, BMI and triglyceride levels than survivors with complications. HbA_1c level is a predictor of macrovascular disease, independently of diabetes duration.