Young adults with generalized epilepsy of unknown origin have a four-fold excess risk of having type 1 diabetes.
Generalized epilepsies of unknown origin, also referred to as “idiopathic” epilepsies, represent about 30 percent of all patients with epilepsy, report Dr. Dougall McCorry, from the Walton Center for Neurology and Neurosurgery, Liverpool, UK, and colleagues.
“Both idiopathic generalized epilepsies and type 1 diabetes mellitus represent serious worldwide problems, because of related medical and social management costs,” they note. Clinical experience suggests that both conditions occur in individuals more frequently than might be expected by chance.
To investigate, the researchers examined whether the prevalence of type 1 diabetes is increased in a group of young adults with idiopathic generalized epilepsy compared with the prevalence in a study that included participants from the general population.
A total of 518 subjects between the ages of 15 and 30 years with idiopathic generalized epilepsy were identified. Of these, seven patients had type 1 diabetes.
Of 150,000 subjects in the same age group in a general population survey, 465 cases were identified. A significant excess of type 1 diabetes was observed in the idiopathic generalized epilepsy group, with an odds ratio of 4.4.
“Idiopathic generalized epilepsy has an increased prevalence in the type 1 diabetes population than the general population if our observations are correct,” McCorry and colleagues point out.
When they looked into the seven cases of diabetes in the idiopathic generalized epilepsy group, they found that “age of onset, where available, demonstrates type 1 diabetes preceded the onset of idiopathic generalized epilepsy in…six cases.”
This could mean that diabetes causes idiopathic generalized epilepsy, or just that the two conditions have different ages of onset.
The team suggests it is possible that some type 1 diabetics develop seizures only in response to low blood sugar or have unrecognized epilepsy with only occasional spontaneous seizures.
Annals of Neurology, January 2006