Renal function as an effect modifier of intensive glucose control in delaying cognitive function decline among individuals with type 2 diabetes: A revisit to the ACCORD MIND trial.

AIM

Dysglycaemia accelerates cognitive decline. Intensive glucose control may help delay or prevent cognitive function decline (CFD). We aimed to determine how patient characteristics influence the effect of intensive glucose control [glycated haemoglobin (HbA1c) <6.0%] on delaying CFD in people with type 2 diabetes.

RESEARCH DESIGN AND METHODS

In this post-hoc analysis of 2977 type 2 diabetes participants from the ACCORD MIND trial, we applied the causal forest and causal tree algorithms to identify the effect modifier of intensive glucose control in delaying CFD from 68 variables (demographics, disease history, medications, vitals and baseline biomarkers). The exposure was intensive versus standard glucose control (HbA1c <6.0% vs. 7.0%-7.9%). The main outcome was cognitive function changes from baseline to the 40th month follow-up, which were evaluated using the digit symbol substitution test, Rey auditory verbal learning test, mini-mental state examination and Stroop test. We used Cohen's d, a measure of standardized difference, to quantify the effect size of intensive glucose control on delaying CFD.

RESULTS

Among all the baseline characteristics, renal function was the most significant effect modifier. Participants with urinary albumin levels <0.4 mg/dl [absolute function change (AFC): 0.51 in mini-mental state examination, 95% confidence interval (CI): 0.04, 0.98, Cohen's d: 0.25] had slower CFD with intensive glucose control. Patients with preserved renal function (estimated glomerular filtration rate between 60 and 90 ml/min/1.73 m) were associated with small benefits (AFC: 1.28 in Stroop, 95% CI: 0.28, 2.27, Cohen's d: 0.12) when undergoing intensive glucose control. Conversely, participants with an estimated glomerular filtration rate <60 ml/min/1.73 m (AFC: -0.57 in the Rey auditory verbal learning test, 95% CI: -1.09, -0.05, Cohen's d: -0.30) exhibited faster CFD when undergoing intensive glucose control. Participants who were <60 years old showed a significant benefit from intensive glucose control in delaying CFD (AFC: 1.08 in the digit symbol substitution test, 95% CI: 0.06, 2.10, Cohen's d: 0.13). All p < .05.

CONCLUSIONS

Our findings linked renal function with the benefits of intensive glucose control in delaying CFD, informing personalized HbA1c goals for those with diabetes and at risk of CFD.