Diabetes mellitus: a risk factor for seizures in the elderly-a population-based study

Aims: To evaluate the association between diabetes mellitus (DM) and risk of seizures in a well-defined elderly population.

Methods: The administrative databases of the Lombardy region (a 10 million population area in Northern Italy) were used to identify persons aged 65 years or older with DM (defined by prescription of antidiabetic drugs and/or through ICD-9 CM code and/or exemption code for diabetes) during the year 2002. Seizure-free DM subjects were followed until 2012 in search of individuals with incident seizures (identified through ICD-9 CM codes for epilepsy/seizures or ATC codes for antiepileptic drugs associated with the prescription of an electroencephalogram). To adjust for confounding, comorbidities having epileptogenic potential were also identified through the ICD-9 CM codes.

Results: The population at risk included 1,494,071 persons. Of these, 136,941 seizure-free patients had DM. At the end of follow-up, the cumulative time-dependent incidence of seizures was 3.0% in DM patients and 1.9% in No-diabetic individuals (hazard ratio, HR 1.47; 95% confidence interval, 1.41-1.53, adjusted for age classes, sex, comorbidities and number of hospital admission). The HR was unchanged in patients with no history of stroke. The cumulative incidence of seizures after DM increased with the number of hospital admissions.

Conclusions: DM is an independent risk factor for seizures in elderly individuals. In diabetic patients, the risk of seizures increases with the number of comorbidities, supporting the role of vascular disease as a cause of seizures.