Increased parathyroid hormone is associated with higher fasting glucose in individuals with normocalcemic primary hyperparathyroidism and prediabetes: A pilot study.

AIMS: This pilot study aimed to evaluate differences in glycemic parameters between patients with prediabetes and normocalcemic primary hyperparathyroidism (NPHPT) and controls with prediabetes and normal parathyroid hormone (PTH) and calcium concentrations.

METHODS

20 patients with NPHPT and prediabetes and 42 age-, gender-, and body mass index-matched controls with prediabetes were included. Glycemic parameters [fasting glucose (fGlu), glycosylated hemoglobin (HbA1c), fasting insulin (fIns)] were evaluated. Homeostasis Model Assessment was used for estimating insulin secretion (HOMA-B) and resistance (HOMA-IR). Participants underwent a 75-g oral glucose tolerance test.

RESULTS

HbA1c (5.9 ± 0.0 vs 5.9 ± 0.0%, p = 0.44), HOMA-IR (3.7 ± 1.2 vs 2.9 ± 0.2, p = 0.48), HOMA-B (117.8 ± 31.8 vs 146.9 ± 22.0%, p = 0.14), fIns (14.0 ± 4.3 vs 12.2 ± 1.1 μIU/ml, p = 0.53) and 2-hour post-load glucose concentrations (157.2 ± 2.2 vs 152.2 ± 2.0 mg/dl, p = 0.07), were nondifferent in the two groups. Higher fGlu levels were evident in the NPHPT, compared to the control group (105.6 ± 2.8 vs 98.2 ± 1.8 mg/dl, p = 0.01). fGlu demonstrated a positive correlation with PTH concentrations (rho = 0.374, p = 0.005).

CONCLUSIONS

Individuals with NPHPT and prediabetes present an unfavorable glycemic profile compared to age-matched people with prediabetes, suggesting a direct adverse effect of elevated PTH on glucose homeostasis.