Excess Mortality in Patients With Type 1 Diabetes Without Albuminuria—Separating the Contribution of Early and Late Risks

Abstract

OBJECTIVE The current study investigated whether the risk of mortality in patients with type 1 diabetes without any signs of albuminuria is different than in the general population and matched control subjects without diabetes. RESEARCH DESIGN AND METHODS We studied a nationwide, population-based Finnish register of 10,737 patients diagnosed with type 1 diabetes during 1980–2005 and followed for 10 years and 2,544 adults with long-standing diabetes drawn from the Finnish Diabetic Nephropathy Study (FinnDiane). Mortality was compared with the general Finnish population and 6,655 control subjects without diabetes. RESULTS The standardized mortality ratio (SMR) was increased during the first 10 years after the diagnosis (2.58 [95% CI 2.07–3.18], P < 0.001). Mortality in adults with long-standing diabetes, but without albuminuria, was no different from that of the general population (1.02 [0.84–1.22], P = 0.83). However, it was higher compared with that of control subjects without diabetes (1.33 [1.06–1.66], P = 0.01). Excess mortality was largely due to acute diabetes complications and ischemic heart disease, which remained more than fourfold higher (mortality rate ratio 4.34 [2.49–7.57]) in adults with type 1 diabetes than in control subjects without diabetes, despite the absence of albuminuria. By contrast, deaths due to alcohol and drugs were reduced in adults with type 1 diabetes (P = 0.007), especially in men. CONCLUSIONS Excess mortality in type 1 diabetes is the result of its complications. Acute complications drive an increased SMR in the first years. In individuals who remain free of albuminuria, mortality due to ischemic heart disease is still four times higher, and acute complications also occur.