Prediabetes Causing Post Stroke Cognitive Impairment

Scientists at Wenzhou Medical University in China have established an association between prediabetes and the development of post-stroke cognitive impairment (PSCI). Prediabetes is a state between normal blood-sugar conditions and diabetes mellitus (DM). Cognitive impairment after stroke is fairly common, but varies based on country, race and diagnostic criteria. Prediabetes and DM are both common risk factors of stroke. DM has already been related to PSCI by previous studies, however, as far as the authors’ understanding goes, this was the first study to explore a relationship between PSCI and prediabetes.

Prediabetes is a strong predictor of DM and can be diagnosed by characteristic changes in blood sugar level. Based on these levels, the patients were categorized into diabetes mellitus (DM), prediabetes and non-DM groups. The study evaluated the cognitive function of 201 patients 1 month after a stroke.The study diagnosed 74 of the total 201 patients with PSCI. Data showed the percentage of PSCI patients to be 18.1%, 35.7% and 49.3% respectively for the non-DM, prediabetes, and DM patients.

Analysis based on sex and smoking history surprisingly showed that patients who were female and non-smokers are at a greater risk of PSCI than any other group.

A statistical test conducted to adjust for confounders showed an association between PSCI and prediabetes. Confounders lead to bias that distorts the magnitude of the relationship between two factors of interest. For example, results showed that age and educational level also influenced the effects of prediabetes on PSCI. However, this was found to be untrue after adjusting for confounders.

The study included individuals who had suffered a stroke less than 7 days before admission and were diagnosed using CT scan and MRI. However, it excluded all individuals who had a history of severe depression and other psychiatric disorders or severe nervous system diseases. PSCI was evaluated by experienced neurological physicians who were not aware about the patients’ clinical examination and lab results.

The results were strong, but there were limitations to the study. The use of antidiabetic medicine post stroke was not recorded. Patients with speech and language disorders were excluded, which could have cause biases in the study. Moreover, the time span between stroke and PSCI assessment would have provided more appropriate results if it was longer than one month, for example, 3 to 6 months. Nevertheless, the study proved that prediabetes is a determinant of PSCI and suggests prediabetes patients to maintain normal blood sugar level as a preventive measure.

Reference:

Wang, Q., Zhao, K., Cai, Y., Tu, X., Liu, Y., He, J. 2017. Prediabetes is associated with post-stroke cognitive impairment in ischaemic stroke patients. Elsevier/North-Holland Biomedical Press 1687:137-143

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