Relationship Between Baseline Glycemic Control and Cognitive Function in Individuals With Type 2 Diabetes and Other Cardiovascular Risk Factors

Abstract

OBJECTIVE -Diabetes is associated with cognitive decline and dementia. However, the relationship between the degree of hyperglycemia and cognitive status remains unclear. This was explored using baseline cognitive measures collected in the ongoing Memory in Diabetes (MIND) substudy of the Action to Control Cardiovascular Risk in Diabetes (ACCORD) trial. RESULTS -A statistically significant age-adjusted association was observed between the A1C level and the score on all four cognitive tests. Specifically, a 1% higher A1C value was associated with a significant 1.75-point lower DSST score (95% CI Ϫ1.22 to Ϫ2.28; P Ͻ 0.0001), a 0.20-point lower MMSE score (Ϫ0.11 to Ϫ0.28; P Ͻ 0.0001), a 0.11-point lower memory score (Ϫ0.02 to Ϫ0.19, P ϭ 0.0142), and a worse score (i.e., 0.75 s more) on the Stroop Test (1.31-0.19, P ϭ 0.0094). The association between the DSST score and A1C persisted in all multiple linear regression models. FPG was not associated with test performance. RESEARCH DESIGN AND METHODSCONCLUSIONS -Higher A1C levels are associated with lower cognitive function in individuals with diabetes. The effect of glucose lowering on cognitive function will be determined by the ongoing ACCORD-MIND trial. Diabetes Care 32:221-226, 2009M ild cognitive impairment represents an important phase on the path from normal cognitive function to dementia. Affected individuals have measurable deficits in cognitive function that may affect their ability to master complex behaviors such as those required for diabetes self-care (1). Moreover, because mild cognitive impairment is more common than frank dementia, its potential population health impact is high. For example, the prevalence of mild cognitive impairment (i.e., predementia) in the Cardiovascular Health Study was 19% in individuals aged Ͼ65 years and 29% in those aged Ͼ85 years.Diabetes is associated with premature mortality and is a risk factor for mild cognitive impairment and both vascular dementia (2-5) and Alzheimer's disease (2,6 -8). Indeed, individuals with diabetes are ϳ1.5 times more likely to experience cognitive decline and frank dementia than individuals without diabetes (9). Precise reasons for the high morbidity and mortality of diabetes remain unknown; however, many studies have demonstrated a link between many of the consequences of diabetes and the degree of hyperglycemia as measured by the A1C or glucose level. Emerging evidence suggests that a relationship between measures of short-term glucose control and cognitive function also exists. For example, in a cross-sectional analysis of 378 high-functioning individuals with diabetes, higher A1C but not fasting plasma glucose (FPG) levels were consistently associated with lower scores on two cogni-

Cognitive Dysfunction in Diabetic Patients with Special Reference to Age of Onset, Duration and Control of Diabetes

“…Similar prevalence of cognitive dysfunction was reported in a previous study by Munshi et al (2006).Their study showed that one-third of the elderly diabetic population had cognitive dysfunction as described by the CIB(clock in a box) test. In the Cardiovascular Health Study, prevalence of mild cognitive dysfunction was 19% in individuals aged more than 65 years and 29% in those aged more than 85 years (Cukierman-Yaffe, et al, 2009). Cukierman et al (2005) showed that individuals with diabetes were 1.5 times more likely to experience cognitive decline and frank dementia than individuals without diabetes.…”

Cognitive function and risks of cardiovascular disease and hypoglycaemia in patients with type 2 diabetes: the Action in Diabetes and Vascular Disease: Preterax and Diamicron Modified Release Controlled Evaluation (ADVANCE) trial

“…A number of studies have reported that cognitive decline is accelerated in patients with diabetes, independently of common cardiovascular risk factors [3][4][5] and is associated with poor glycaemic control [6]. In a recent meta-analysis, patients with type 2 diabetes were estimated to have a 1.5-fold greater risk of cognitive dysfunction and 1.6-fold greater risk of dementia compared with people without diabetes [7].…”

Management of diabetes and dementia

“…1 The DCCT/EDIC study found that glycaemic control was associated with declining cognitive function and the ACCORD-MIND trial noted that, for each 1% rise in Hba1c, there was a 0.14 point drop in MMSE score. 2,3 In addition, studies have noted the effects of hypoglycaemia on increasing risk of cognitive impairment. 4,5 However, there is a paucity of information on the management of diabetes and therapeutic options in dementia, as many patients (with dementia) would be excluded from clinical trials designed to test efficacy and safety of diabetes medications.…”