Aims: There are few cohorts of type 1 diabetes that follow individuals over more than half a century in terms of health outcomes. The aim of this study was to examine associations between type 1 diabetes, diagnosed before age 18, and long-term morbidity and mortality, and to investigate whether cognitive ability plays a role in long-term morbidity and mortality risk.

Methods: In a Swedish cohort, 120 men with type 1 diabetes and 469 without type 1 diabetes were followed between 18 and 77 years of age as regards morbidity and mortality outcomes, and impact of cognitive ability at military conscription for the outcomes. In Cox regression analyses and Kaplan-Meier analyses with log-rank tests, associations between diabetes and cognitive ability respectively, and outcomes (mortality, cardiovascular morbidity and diabetes complications) were investigated.

Results: Men with type 1 diabetes suffered from dramatically higher mortality (HR 4.62, 95% CI: 3.56–5.60), cardiovascular mortality (HR 5.60, 95% CI: 3.27–9.57), and cardiovascular events (HR 3.97, 95% CI: 2.79–5.64) compared to men without diabetes. Higher cognitive ability at military conscription was associated with lower mortality in men without diabetes, but was not associated with any outcome in men with diabetes.

Conclusions: In this historical cohort study with 60 years of follow-up time and a less effective treatment of diabetes than today, mortality rates and cardiovascular outcomes were high for men with type 1 diabetes. Morbidity or mortality did not differ between those that had low to normal or high cognitive ability among men with type 1 diabetes.

What’s new 

• There is little data from Scandinavia on the long-term prognosis of type 1 diabetes before 1970, and no studies that investigate cognitive ability early in life as a predictor of long-term morbidity and mortality in type 1 diabetes.
• Men with type 1 diabetes followed for 60 years had a 4.6 times higher risk of all-cause mortality than men without diabetes. Cognitive ability at 18 years significantly predicted mortality in men without, but not with, type 1 diabetes.
• The results add to the literature describing the prognosis of type 1 diabetes in Scandinavia during the time period from 1934 until today.