A population-based study of epilepsy incidence in association with type 2 diabetes and severe hypoglycaemia.

AIMS: This study was conducted to investigate potential link between type 2 diabetes mellitus (T2DM) and epilepsy, and the role of severe hypoglycaemia (SH) might play in the relationship.

METHODS: This was a cohort study based on Taiwan's National Health insurance claims. Totally 751,792 people with T2DM and 824,253 matched controls were identified in 2002-2003 and followed to incidence of epilepsy or end of 2011. We used Cox proportional hazard model to relate epilepsy incidence to separate and joint effects of T2DM and SH. A possible mediation effect of SH on the association between T2DM and epilepsy was analyzed.

RESULTS: Over a 10-year follow-up, patients with T2DM had a higher incidence rate of epilepsy than controls (35.0 vs 21.9 per 10,000 person-years). After controlling for potential confounders including SH, T2DM increased the hazard of epilepsy by some 50%. The stratified analysis further indicated that T2DM (hazard ratio (HR)=1.44, 95% confidence interval (CI) = 1.40-1.47), and SH (HR = 2.22, 95% CI = 1.76-2.81) were both independent risk factors for epilepsy. SH did not modify but mediated 12% of the association between T2DM and epilepsy.

CONCLUSION: Our findings supported that SH may increase the risk of epilepsy, and that T2DM may increase risk of epilepsy independent of SH.