Altered Calcium Homeostasis Is Correlated With Abnormalities of Fasting Serum Glucose, Insulin Resistance, and β-Cell Function in the Newfoundland Population

Abstract

Alteration of extracellular calcium concentration may be involved in glucose metabolism in a number of pathways. The present study was designed to investigate the relationship between total serum calcium and 1) fasting serum glucose, 2) insulin, 3) insulin resistance, and 4) beta-cell function in 1,182 healthy subjects from the province of Newfoundland and Labrador, Canada. All variables were log10 transformed, and confounding factors including age, trunk fat percentage, serum phosphorus, magnesium, 25-OH vitamin D, and parathyroid hormone were adjusted before analyses. Significant positive correlations between glucose and insulin resistance with calcium were found in both sexes, whereas an inverse correlation between beta-cell function and calcium was found only in women. Similar results were found in medication-free women and men, as well as in pre- and postmenopausal women. Subjects with low calcium levels had the lowest concentration of glucose and the least insulin resistance, whereas subjects with high calcium levels had the highest concentration of glucose and insulin resistance in women but not in men. This relationship remained after calcium was adjusted for 25-OH vitamin D and parathyroid hormone. Our results suggest that alteration of serum calcium homeostasis is significantly correlated with the abnormality of glucose level, insulin resistance, and beta-cell function.

Serum calcium is independently associated with insulin sensitivity measured with euglycaemic–hyperinsulinaemic clamp in a community-based cohort

“…The lack of association between serum calcium and insulin secretion is consistent with prior studies. Sun and co-workers reported that HOMA-estimated beta cell function was negatively associated with calcium in females but not in males [13]. Furthermore, in a previous investigation of the ULSAM cohort when the participants were 50 years old, no association was found between serum calcium and insulin secretion, as estimated by the intravenous glucose tolerance test [12].…”

“…Three previous large-scale studies have investigated the relationship between serum calcium and insulin sensitivity and secretion [10,12,13]. In these studies, increasing serum levels of calcium were associated with impaired insulin sensitivity as assessed by fasting insulin or HOMA.…”

“…Intracellular calcium disturbances have been suggested as the factor linking the wide range of abnormalities of the metabolic syndrome, such as hypertension, insulin resistance and obesity [8,9]. A few previous epidemiological investigations have explored the associations between extracellular serum levels of calcium, insulin sensitivity and secretion [10][11][12][13]. However, previous studies have been limited by the use of surrogate markers of insulin sensitivity and secretion [10][11][12][13].…”

“…A few previous epidemiological investigations have explored the associations between extracellular serum levels of calcium, insulin sensitivity and secretion [10][11][12][13]. However, previous studies have been limited by the use of surrogate markers of insulin sensitivity and secretion [10][11][12][13]. All previous epidemiological studies have included subjects with diabetes or IFG and IGT [10][11][12][13], making it difficult to evaluate the independent relationship of serum calcium with the underlying causes of pathologically increased levels of glucose.…”

“…All previous epidemiological studies have included subjects with diabetes or IFG and IGT [10][11][12][13], making it difficult to evaluate the independent relationship of serum calcium with the underlying causes of pathologically increased levels of glucose. Furthermore, all previous studies have included individuals with supra-and subnormal levels of calcium [10][11][12][13] and our knowledge of the relationship between serum calcium within the normal range and insulin sensitivity and secretion is limited.…”