Abstract

Objective: Patients with type 2 diabetes have an increased risk of a reduction in cognitive function. We investigated the hypothesis that plasma glucose is associated with a reduction in episodic and/or semantic memory already in nondiabetic subjects.

Research Design and Methods: We linked two large population-based data sets in Sweden. Firstly, the Betula study where a random sample from the population aged 35–85 years was investigated for cognitive function including episodic and semantic memory. Secondly, the Västerbotten Intervention Program, a health survey with subjects aged 40, 50 and 60 years. It includes measuring of fasting and 2-hour plasma glucose, along with other risk factors for diabetes and cardiovascular disease. We identified 411 (M/F 179/232, mean age 50.6 ±8.0 years) nondiabetic subjects, free from dementia, who had participated in the two surveys within six months.

Results: Women had better episodic (score 7.37 ±1.42) and semantic memory (score 16.05 ±2.76) than men (score 6.59 ±1.29 and 15.15 ±2.92, respectively, p<0.001 for both). In an adjusted multivariate model fPG and 2hPG were significantly negatively associated with episodic memory (fPG: B −0.198, SE 0.068, Beta −0.209, p=0.004 and 2hPG: B −0.061, SE 0.031, Beta −0.148, p=0.048, respectively) in women but not in men. The association was not found in relation to semantic memory.

Conclusions: We conclude that an increase in plasma glucose is associated with impairment in episodic memory in women. This could be explained by a negative effect on the hippocampus caused by raised plasma glucose levels.