Patients with prediabetes improve insulin resistance after surgery for primary hyperparathyroidism.

Background: The objective of this study was to evaluate the evolution of insulin resistance at 12 months after parathyroidectomy for primary hyperparathyroidism according to the preoperative severity of glucose metabolism abnormalities.

Methods: Observational study of patients who underwent parathyroidectomy between 2016 and 2021. Prediabetes and insulin resistance were defined as fasting glucose ≥1.00 g/L (American Diabetes Association) and homeostatic model assessment of insulin resistance >2.5, respectively.

Results: A total of 231 patients were included. Preoperatively, 75 patients (32%) had prediabetes, and 108 patients (47%) had insulin resistance. At 12 months postoperative, homeostatic model assessment of insulin resistance values significantly decreased in patients with prediabetes (-0.69; P = .04) and in patients with insulin resistance (-0.85; P < .001). In patients with prediabetes, 48/75 (64%) decreased their insulin resistance, including 15/48 (31%) with normalization of fasting glucose. In multivariate analysis, preoperative prediabetes (1.82, 1.03-3.21; P = .037) or preoperative homeostatic model assessment of insulin resistance >2.5 (3.90, 2.23-6.75; P < .001) remained independent predictors for insulin resistance reduction observed between preoperative and 12 months postoperative.

Conclusion: Parathyroidectomy is more likely to reduce insulin resistance in patients with primary hyperparathyroidism and prediabetes or in patients with higher preoperative homeostatic model assessment of insulin resistance values. These data support the use of the preoperative prediabetes criterion in addition to the international workshop criteria for parathyroidectomy to better select patients for surgery.