Background: Diabetes has strongly been linked to atrial fibrillation, ischaemic heart disease and heart failure. The epidemiology of these cardiovascular diseases is changing, however, due to changes in prevalence of obesity-related conditions and preventive measures. Recent population studies on incidence of atrial fibrillation, ischaemic heart disease and heart failure in patients with diabetes are needed. Methods: A dynamic longitudinal cohort study was performed using primary care databases of the Julius General Practitioners’ Network. Diabetes status was determined at baseline (1 January 2014 or upon entering the cohort) and participants were followed-up for atrial fibrillation, ischaemic heart disease and heart failure until 1 February 2019. Age and sex-specific incidence and incidence rate ratios were calculated. Results: Mean follow-up was 4.2 years, 12,168 patients were included in the diabetes group, and 130,143 individuals in the background group. Incidence rate ratios, adjusted for age and sex, were 1.17 (95% confidence interval 1.06–1.30) for atrial fibrillation, 1.66 (1.55–1.83) for ischaemic heart disease, and 2.36 (2.10–2.64) for heart failure. Overall, incidence rate ratios were highest in the younger age categories, converging thereafter. Conclusion: There is a clear association between diabetes and incidence of the major chronic progressive heart diseases, notably with heart failure with a more than twice increased risk.