Clinical impact of type 1 and type 2 diabetes mellitus in atrial fibrillation and the effect of severe hypoglycaemia: a nationwide cohort study

Abstract Background Both atrial fibrillation (AF) and diabetes mellitus (DM) are common chronic conditions associated with a significant disease burden. Diabetes increases the risk of AF and the presence of both diseases is associated with higher risk of all-cause mortality and complications. We aimed to compare prognosis individuals with type 1 (T1DM) and type 2 (T2DM) diabetes, against those without DM, in a nationwide cohort of patients with AF and second, to study the outcomes in cases of severe hypoglycaemia amongst those with DM. Methods Based on the France nationwide administrative hospital-discharge database, we collected information for all AF patients seen in French hospitals between 2014 and 2022. Among 3,311,634 patients identified with AF, 694,610 (21.0%) had diabetes: 37,218 (1.1%) with T1DM and 657,392 (19.9%) with T2DM. History of severe hypoglycaemia was defined as a primary or secondary hospital ICD-10 diagnosis of E16.0, E16.1, E16.2, E10.0, E11.0, E12.0, E13.0, or E14.0 and was identified in 22,717 patients (3.1% of those with T1DM and 3.3% of those with T2DM). Adverse outcomes were investigated during follow-up until 31 December 2022. Hazard ratios (HRs) and 95% confidence intervals (CIs) were calculated using Cox model and were adjusted for age, sex and comorbidities (hypertension, obesity, smoking, alcohol abuse, coronary artery disease, heart failure, valve disease, presence of pacemaker or implantable cardioverter defibrillator, peripheral artery disease, stroke, chronic lung disease, chronic kidney disease, dementia and history of cancer). Results Using individuals without diabetes as reference, the adjusted HRs indicated an increased risk in patients T1DM and in those with T2DM for all-cause death, cardiovascular death, HF, MI, ischemic stroke, dementia, VT/VF and cardiac arrest (HRs ranging from 1.19 to 1.69 in T1DM and from 1.10 to 1.41 in T2DM, all p <0.0001, see Table 1). Among patients with diabetes, those with a history of severe hypoglycaemia had increased risks of all-cause death, dementia and cardiac arrest in case of T1DM and an increased risk of all-cause death, cardiovascular death, HF, MI, dementia and cardiac arrest in case of T2DM (see Table 2). Conclusion Presence of diabetes (regardless of type) is associated with an increased risk of premature death, cardiovascular events and dementia in patients with AF. This increase seems more pronounced in T1DM than in T2DM. A history of severe hypoglycaemia is associated with a much worse prognosis in patients with T1DM or T2DM.