Spotlight on diabetes and memory

One recent study found that many patients with diabetes frequently forget to take their medications, while another analyzed the association between diabetes and brain volume and cognitive performance among older people.

Two recent studies looked at memory function and its relationship to diabetes.

The first study, published by Diabetic Medicine on Dec. 14, 2018, was based on a survey that asked Australian patients with diabetes about whether they commonly forget to take their glucose-lowering medications. It included 901 patients with type 1 diabetes and 927 patients with type 2 diabetes. Almost a quarter of them (24% of those with type 1, 23% of those with type 2) reported having forgotten their medication at least once over the previous 14 days. The participants' subjective memory performance was also measured using the Prospective and Retrospective Memory Questionnaire. The study found an association between forgetting medication and reporting prospective memory slips in both patients with type 1 diabetes (odds ratio [OR], 1.09; 95% CI, 1.05 to 1.13; P<0.001) and those with type 2 diabetes (OR, 1.10; 95% CI, 1.05 to 1.15; P<0.001). Forgetting medications was also associated with younger age in both types of diabetes. In patients with type 1 diabetes, insulin pump use, less frequent blood glucose checks, and higher HbA1c level were all associated with forgetting medications.

The results show that forgetting medication is relatively common among patients with diabetes, a finding that could have potential impact on glycemic control, the study authors said. “Not taking diabetes medication was more likely to be due to forgetting than intentionally skipping it,” they noted. The association between forgetting medication and not checking blood glucose could be useful in clinical practice, if infrequent self-monitoring were used as a prompt for clinicians to ask whether a patient forgets to take medication. The study's findings on prospective memory slips suggest that “medication reminders (auditory and/or visual) may be important in improving medication adherence in people with diabetes,” the authors said.

The second study, published by Diabetologia on Dec. 13, 2018, looked at brain atrophy and cognitive decline in older patients with and without diabetes. It included adults in Tasmania, Australia, who were ages 55 to 90 years and without dementia at baseline (348 with diabetes and a mean age 68.2 of years, and 357 without diabetes and a mean age of 72.5 years). All underwent brain MRI and neuropsychological measurements at three time points over 4.6 years. After adjustment for age, sex, education, and vascular risk factors, the study found a decline in verbal memory and fluency over time in the patients with diabetes that was significantly greater than in the patients without diabetes. The patients with diabetes had lower brain volume at baseline, but diabetes was not associated with decline in brain volume during the study's follow-up.

The results suggest an impact of diabetes on cognitive function that begins before old age, the study authors said. The lack of an association with brain atrophy was contrary to their hypothesis and may indicate that changes in brain atrophy resulting from diabetes begin in midlife, according to the authors. They noted that previous research on associations between cognitive decline and diabetes has had mixed findings, which may reflect differences in studies' populations, lengths of follow-up, and cognitive measures. “The effects of type 2 diabetes and poor metabolic health at midlife, and the impact of accrual of cerebrovascular lesions at older age, both deserve further study to inform preventative efforts against dementia,” they concluded.