Body mass index predicts insulin sensitivity during cardiac surgery: a prospective observational study.

PURPOSE: Taking into account the previously described link between body weight and diabetes mellitus (DM) in non-surgical patients, and the understanding that the degree of intraoperative insulin resistance is a predictor of adverse clinical outcomes, we investigated the relationship between body mass index (BMI) and insulin sensitivity during cardiac surgery.

METHODS: We prospectively enrolled 400 patients scheduled for elective cardiac surgery and divided them into groups based on the presence or absence of type-2 DM. They were further categorized into four subgroups based on their BMI: group 1- normal weight, BMI 18.5-24.9 kg·m-2 ; group 2 - overweight, BMI 25-29.9 kg·m-2 ; group 3 - obese, BMI 30-34.9 kg·m-2 ; group 4 - morbidly obese, BMI ≥ 35 kg·m-2 . Insulin sensitivity was assessed using the hyperinsulinemic-normoglycemic clamp technique during surgery. We also analyzed the association of BMI, quality of postoperative glycemic control, and postoperative outcomes.

RESULTS: A linear negative relationship between BMI and insulin sensitivity (r = 0.42, P < 0.001) was observed, independent of the patients' diabetic state. There was also a positive correlation between BMI and postoperative glycemia (r = 0.30, P < 0.001) though the relationship between BMI and major and infectious complication was not significant (P = 0.56, P = 0.10, respectively).

CONCLUSIONS: Patient BMI may be used as a simple predictor of insulin sensitivity during cardiac surgery and as a predictor of the quality of postoperative glycemic control. A larger cohort will be necessary to evaluate the association of BMI, perioperative insulin resistance, and clinical outcomes.