Type 2 Diabetes with Comorbid Depression in Relation to Cognitive Impairment: an Opportunity for Prevention?

Studies show poor glycemic control is associated with increased risk of dementia among patients with Type 2 diabetes, indicating potential for prevention of dementia with improved glycemia. Emerging evidence suggests that a relationship between short-term glycemic control and cognitive function exists in Type 2 diabetes. However, detailed mechanisms relating diabetic dementia are lacking, as other concurrent conditions, such as depression, may also increase the risk of dementia in Type 2 diabetes. We examined the effects of glycemic control and depression on cognitive function in 88 patients (mean age, 67 ± 4 years) whose A1c (glycosylated hemoglobin) levels, comorbid depression, mini-mental state examination (MMSE) scores were recorded at baseline. Seventeen patients had depression; 14 agreed on anti-depressants. In 6 months, 69 patients reached A1c goal of < 7% (A1c from 9.7 ± 0.8 to 6.4 ± 0.3) while cognition improved significantly (MMSE scored from 20.2 ± 3.5 to 26.2 ± 2.1, p < 0.05). Cognitive increment in controlled diabetes was more consistently observed if their underlying depression was effectively treated (n - 14). Nineteen patients did not reach A1c goal of < 7% (A1c from 9.6 ± 0.9 to 8.9 ± 0.9) while cognitive increment was minimal (MMSE scored from 20.6 ± 4.9 to 21.3 ± 5.1, p > 0.05). Cognitive decrements were observed among depressed diabetics who refused anti-depressants. Multivariate analysis adjusted for age, education, alcohol use, and other variables yielded similar results. We found controlled glycemia and depression prevent cognitive decline. Further research into mechanisms of cognitive impairment in diabetes may allow us to challenge the concept of dementia in those patients as an irremediable disease.