Perioperative neurocognitive disorder changes in elderly diabetes patients within 30 days after surgery: a retrospective cohort study

Background Perioperative neurocognitive disorders (PND) are a common central nervous system complication that predominantly affects the elderly. PND after surgery includes postoperative delirium (POD), delayed neurocognitive recovery up to 30 days (DNR), and postoperative neurocognitive disorder up to 12 months. Diabetes is an important independent risk factor for PND. Over the years, few studies have assessed the incidence of PND and the difference in serum biomarkers between diabetic and non-diabetic patients. We sought to examine the difference in the incidence of PND between elderly diabetic and non-diabetic patients in China and identify the risk factors of PND in elderly diabetics. Methods We conducted a secondary and exploratory data analysis from our prior studies, including patients aged 65 years or older who underwent non-cardiac elective surgery with general anesthesia. We used the Confusion Assessment Method for the Intensive Care Unit (CAM-ICU) and Montreal Cognitive Assessment (MoCA) to assess patient cognition. Results A total of 236 patients were analyzed; the incidence of PND was significantly higher in diabetic than in non-diabetic patients within 30 days (59.2% vs. 36.8%) ( P = 0.022). Multivariate logistic regression analysis showed that the preoperative MoCA was an independent risk factor for PND (odds ratio, 0.88 [0.8 to 0.97]; P = 0.014), and Hosmer–Lemeshow tests showed that it could predict PND in diabetic patients ( P = 0.360). According to the maximum Youden index, the optimal cutoff for preoperative MoCA was 21.5 points, yielding a specificity and sensitivity of 88.0% and 55.2% for PND. The levels of glial fibrillary acidic protein (GFAP) and Tau in diabetic patients before and after surgery were significantly higher than in non-diabetic patients among cases of PND ( P = 0.002 and 0.011, respectively). Conclusion The incidence of PND is higher in diabetic than in non-diabetic patients in China, and preoperative MoCA is an independent risk factor for PND in diabetics. Meanwhile, the changes in GFAP and p-Tau in diabetic patients who experienced PND were significantly higher than in non-diabetic ones.