Diabetes mellitus appears to be associated with a markedly increased risk of Alzheimer’s disease, but only in men. Said, Steven D. Edland, Ph.D., at the annual meeting of the American Academy of Neurology. The association between diabetes and this major neurodegenerative disease is attenuated by age, duration of diabetes, and the type of antidiabetic therapy utilized, as well as by gender, added Dr. Edland, an epidemiologist at the Mayo Clinic, Rochester, Minn.
He reported on a National Institute on Aging–sponsored case-control study involving 356 Rochester-area patients with onset of Alzheimer’s disease in 1985-1989 and an equal number of age- and gender-matched controls.
Study participants with a history of diabetes mellitus had nearly twice the risk of Alzheimer’s disease. Risk was increased 6-fold among diabetic men, and a nonsignificant 1.2-fold in diabetic women.
In participants younger than age 80, a history of diabetes carried a 3.2-fold increased risk of Alzheimer’s disease. In those aged 80 or older, however, the risk among diabetics was 1.2-fold higher compared to individuals without diabetes. Also, people with diabetes for over 13 years were no more likely to have Alzheimer’s than were people without diabetes.
Patients whose diabetes was treated with insulin alone had an 8-fold increased risk of Alzheimer’s disease, compared with that of nondiabetic controls; untreated diabetes was associated with a 1.8-fold increased risk. But diabetes treated only with oral agents did not confer an increased risk of Alzheimer’s disease, compared with that of controls.