Patients with
primary hyperparathyroidism have
impaired glucose tolerance more often than do controls, and parathyroid resection sometimes improves this derangement. However, it is unclear whether serum
calcium (Ca) or
parathyroid hormone (PTH) is more strongly related to impaired
glucose metabolism in subjects without
primary hyperparathyroidism. In this cross-sectional study, we examined patients with
type 2 diabetes mellitus (DM) (271 men and 209 women) and analyzed the relationships between serum concentrations of Ca or intact PTH and DM-related variables. Simple regression analyses showed that the level of serum Ca was significantly and positively correlated with the levels of fasting plasma
glucose, immunoreactive
insulin, and homeostasis model assessment
insulin resistance in men (P < .05), but not in women. In contrast, intact PTH was not significantly correlated with DM-related parameters in either sex. Multiple regression analyses showed that the significant and positive correlations between serum Ca vs fasting plasma
glucose and homeostasis model assessment
insulin resistance in men still remained after adjustment for intact PTH as well as age,
body weight, height,
creatinine,
albumin,
phosphate, bone metabolic markers, and
estradiol (P < .05). Serum Ca level is positively associated with impaired
glucose metabolism, independent of PTH or bone metabolism, in men with type 2 DM.