By Colin Kenny, Editor – Diabetes Distilled
Investigators wanted to discover whether there was an association between treatment choices for diabetes and dementia. They performed a systematic review and meta-analysis of pharmacological treatment of diabetes and incident or progressive cognitive impairment. Antidiabetic drug treatment was not generally associated with incident dementia. Differential effects were, however, found across drug classes, with insulin therapy being associated with a signal of harm and thiazolidinediones having potentially protective effects on cognition. There was nearly a twofold increase in the likelihood of incident dementia in those who experienced severe hypoglycaemic episodes.
About one in ten people with dementia have diabetes and diabetes is a risk factor for the development of dementia. Cognitive decline in older people with diabetes is associated with poor glycaemic control and a higher frequency of severe hypoglycaemic episodes. Despite these associations, the impact of diabetes management on cognitive decline remains uncertain. The authors of this paper performed a systematic review including 37 studies, 13 of which were incorporated into the quantitative analysis.
The investigators found the effects to be different across drug classes: insulin therapy was associated with a signal of harm but thiazolidinediones had potentially protective effects on cognition. Severe hypoglycaemia increased the likelihood of incident dementia twofold. The risk of cognitive impairment increases with the duration and severity of diabetes.
Investigators speculate that there is a complex, possibly bidirectional, relationship between severe hypoglycaemia and cognitive deficit. Treatment of patients with diabetes and dementia should focus on avoiding symptomatic hyperglycaemia and not on achieving strict blood glucose targets, which would mitigate the risk of hypoglycaemia.
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