An association between diabetes and dementia is already observed through studies. In this new prospective study from Seattle's Group Health Cooperative, researchers sought to determine whether average glucose levels in people without diabetes predict development of dementia.

The study involved 2067 older adults (mean age 74; 11% with diabetes) who had no evidence of dementia at baseline. During a median follow-up of 7 years, 25% of participants were diagnosed with dementia. Among participants who did not have diabetes, risk for developing dementia increased with increasing average glucose levels, after adjustment for potentially confounding variables. For example, in those whose average glucose level was 115 mg/dL, relative risk for dementia was 18% higher than in those whose average glucose level was 100 mg/dL. Among participants who had diabetes, relative risk for dementia was 40% higher in those whose average glucose level was 190 mg/dL compared with 160 mg/dL.