Presence and Determinants of Cardiovascular Disease and Mortality in Individuals With Type 1 Diabetes of Long Duration: The FinnDiane 50 Years of Diabetes Study

Abstract

OBJECTIVE The aim of this study was to determine the incidence of cardiovascular disease (CVD) and mortality as well as their risk factors in type 1 diabetes (T1D) of >50 years’ duration. RESEARCH DESIGN AND METHODS From 5,396 individuals included in the Finnish Diabetic Nephropathy Study (FinnDiane), 729 diagnosed in 1967 or earlier survived with T1D for >50 years. In this FinnDiane 50-year cohort, cumulative incidence of CVD events was assessed from the diagnosis of diabetes, and the excess CVD risk, compared with 12,710 matched individuals without diabetes. In addition, risk factors for different types of CVD (both nonfatal and fatal) and mortality were analyzed, and cause-specific hazard ratios were estimated during a median follow-up of 16.6 years from the baseline visit (median duration of diabetes 39 years at baseline). RESULTS In individuals with diabetes duration of >50 years, the 60-year cumulative incidence of CVD from the diagnosis of diabetes was 64.3% (95% CI 62.5–66.0). Compared with individuals without diabetes, the standardized incidence ratio for CVD was 7.4 (6.5–8.3); in those with normoalbuminuria, it was 4.9 (4.0–5.9). Mean HbA1c and HbA1c variability, dyslipidemia, BMI, kidney disease, age, and diabetes duration were the variables associated with incident CVD. In particular, HbA1c was associated with peripheral artery disease (PAD). The standardized mortality ratio compared with the Finnish background population was 3.2 (2.8–3.7). The factors associated with mortality were diabetes duration, increased HbA1c variability, inflammation, insulin resistance, kidney disease, and PAD. CONCLUSIONS Individuals with T1D of very long duration are at a high risk of CVD. In addition, throughout the lifespan, optimal glycemic control remains central to CVD and excess mortality prevention.