The effects of body mass index on insulin resistance in patients undergoing total hip arthroplasty: a pilot study.

PURPOSE: We aimed to examine the effects of body mass index (BMI) on insulin resistance (IR), glycaemic control and adverse events in patients undergoing total hip arthroplasty (THA). METHODS: A total of 118 patients undergoing THA were enrolled in this prospective cohort study and divided into two groups based on their BMI: Group A (n = 50, 18.5 ≤ BMI < 24 kg/m2) and Group B (n = 68, BMI ≥ 24 kg/m2). IR was calculated using Homeostasis Model Assessment 2 (HOMA2). Insulin resistance indicators, fasting plasma glucose (FPG), inflammatory markers, blood loss, length of stay and complications were compared between the two groups. RESULTS: Multivariate analysis using generalized estimating equations revealed that BMI and surgery stress were risk factors for IR (P < 0.001). These two factors exhibited significant interactions for HOMA2-IR on post-operative day one (Exp (B) = 1.880, P = 0.003), accompanied by a higher level of FPG (Group B versus Group A, P = 0.004). Furthermore, subgroup analysis based on the IR value demonstrated that patients in Group B with a HOMA2-IR greater than 2.25 after surgery were at increased risk of wound complications (P = 0.045). Similarly, our results showed that the rate of post-operative hyperglycaemia was notably higher in Group B than in Group A (P = 0.013). CONCLUSION: Patients with high BMI may experience significantly elevated IR and increased risk of hyperglycaemia and wound complications after THA. Therefore, routine glycaemia monitoring should be suggested for those patients during peri-operative period to optimize surgical stress management.