Type 2 diabetics with severe low blood sugar may have an increased risk of developing Alzheimer’s disease, according to a new study.

Older adults who have been hospitalized for severe low blood sugar are at a 32% greater risk for developing Alzheimer’s, according to the research from Kaiser Permanente in Oakland, CA. Reasons for the association are unclear, said researchers, who followed 16,667 seniors with type 2 diabetes between 1980 and 2007. The study looked only at the association between the two diseases, however, and does not prove a cause-and-effect association. Currently there are an estimated 24 million Americans with type-2 diabetes, and that number is likely to rise with the growing population of seniors, researchers say.

Though scientists aren’t sure what causes the correlation, fluctuating glucose levels could be one factor. Another factor could be the toxic effects of high blood sugar, suggested one scientist when commenting on the study, though he noted the effects of those conditions could not be proven in this type of research. The full study appears in the April 15 issue of the Journal of the American Medical Association.