Better diabetes control may improve memory

Better metabolic control of type 2 diabetes can lead to improved "working memory" - the type of memory people use to keep information in their minds for short-periods of time and to complete day-to-day activities.

"Many of the patients with type 2 diabetes may have evidence of mild cognitive dysfunction," Dr. Christopher M. Ryan, from University of Pittsburgh School of Medicine, told Reuters Health. "Improving metabolic control and reducing fasting plasma glucose (sugar) levels can lead to an improvement in learning and memory ability."

Ryan and colleagues investigated whether improvements in metabolic control could ameliorate cognitive dysfunction in 145 older adults with type 2 diabetes and if the improvements are mediated by changes in circulating insulin (with glyburide therapy) or insulin resistance (with rosiglitazone treatment).

Both treatments led to significant reductions in fasting blood sugar after 24 weeks, the authors report in Diabetes Care. Decreases in fasting insulin were seen only in those treated with rosiglitazone.

Working memory improved significantly in both treatment groups, the results indicate, and there were no differences between the glyburide and rosiglitazone groups.

Reductions in fasting plasma glucose were associated with improvements in working memory regardless of the drug used.

Neither treatment was associated with changes in measures of learning ability or cognitive efficiency, the researchers note.

This study, note the authors, shows that "treatment-induced reductions in fasting plasma glucose levels are accompanied by corresponding improvements in cognition, which occur within 24 weeks of therapy initiation."

"What's particularly interesting," Ryan added, "is the fact that we obtained these results in diabetic patients who were in relatively good control. We don't know whether the effects would have been even more pronounced had subjects been in consistently poorer control."

How long the improvement lasts "remains unknown," said Ryan. "Based on the findings of this study, there was no reason to favor one medication over the other, although there were fewer side effects associated with rosiglitazone."

SOURCE: Diabetes Care, February 2006.