Comparison of Postoperative Neurocognitive Function in Older Adult Patients with and without Diabetes Mellitus

Abstract

<b><i>Introduction:</i></b> Delayed neurocognitive recovery (DNR; neurocognitive disorder up to 30 days postoperative) and postoperative neurocognitive disorders (POCD; neurocognitive disorder 1–12 months postoperative) occur frequently after surgery, with diabetes mellitus (DM) suggested to contribute to this. This was a single-center prospective cohort study. The main aim of this study was to investigate the role of DM and preoperative hemoglobin A1c (HbA1c) in the development of POCDs after noncardiac surgery. <b><i>Methods:</i></b> Older adult patients ≥65 years of age scheduled for elective surgery were recruited. The Modified Telephone Interview for Cognitive Status questionnaire (TICS-M), a test of global cognitive functioning, was administered to determine cognition. Preoperative, 30-day postoperative, and 6-month postoperative cognition were compared for patients with and without DM. Cognitive decline was subdivided into mild (1 to 2 standard deviations below controls) and major (≥2 standard deviations below controls) DNR or POCD. Preoperative HbA1c levels were correlated with TICS-M scores. <b><i>Results:</i></b> We analyzed 102 patients [median (IQR [range]) age 72.0 (5 [68–74])]), who were divided into patients with DM (80 patients [78%]) and patients without DM (22 patients [22%]). Baseline cognitive function was similar for both groups. Repeated measures ANOVA showed that mean DM patient TICS-M scores decreased 30 days postoperative (<i>F</i>(2, 200) = 4.0, <i>p</i> = 0.02), with subsequent recovery 6-month postoperative, compared to stable TICS-M scores in non-DM patients. There were significantly more DM patients with DNR than non-DM patients (<i>n</i> = 11 [50%] vs. <i>n</i> = 14 [17.5%]; <i>p</i> = 0.031). There were no between-group differences in mild or major POCD. Higher preoperative HbA1c levels were significantly correlated with decreased 30-day Δcognition scores (<i>F</i>(1, 54) = 9.4, <i>p</i> = 0.003) with an <i>R</i>² of 0.149 (β −0.45, 95% confidence interval: −0.735 to −0.154). <b><i>Conclusions:</i></b> Older adult patients with DM undergoing surgery have an increased risk of DNR compared to older adult non-DM patients, but no increased risk of POCD. In DM patients, higher preoperative HbA1c levels were associated with an increased risk of DNR.