Type 2 diabetes risk associated with high normal serum calcium

Type 2 diabetes, characterized by impaired insulin action, is linked to elevated serum calcium according to a study just published in the journal Diabetes Care. The authors state:

"Insulin resistance and secretion depend on calcium homeostasis. Cross-sectional studies have associated elevated serum calcium levels with markers of impaired glucose metabolism... The aim of the current study was to prospectively investigate the association between albumin-adjusted serum calcium concentrations and type 2 diabetes in subjects at high cardiovascular risk."

They collected data for 7447 men (aged 55 to 80 years) and women (aged 60 to 80 years) at high cardiovascular risk, including 707 individuals who did not have diabetes at baseline over an average of 4.8 years and found a significant correlation between type 2 diabetes and higher serum calcium:

"An increase in serum calcium levels during follow-up was related to an increased risk of diabetes. In comparison with individuals in the lowest tertile (−0.78 ± 0.29 mg/dL), the hazard ratio (HR) and 95% CI for diabetes incidence in individuals in the higher tertile of change (0.52 ± 0.13 mg/dL) during follow-up was 3.48. When albumin-adjusted serum calcium was analyzed as a continuous variable, per 1 mg/dL increase, the HR of diabetes incidence was 2.87. These associations remained significant after individuals taking calcium supplements or having calcium levels out of normal range had been excluded."

In other words, even with albumin-adjusted serum calcium, for every 1 mg/dL increase there was a 287% increase in the risk for type 2 diabetes. Note that this refers to 'high normal' levels of serum calcium, and that calcium supplements had no role.Medscape Medical News quoted study co-author Mònica Bulló, PhD, professor in the Faculty of Medicine and Health Sciences at the Universitat Rovira i Virgili, Reus, Spain:

"Measurement [of serum calcium] could add significance to measurement of fasting glucose...Calcium is involved in several metabolic pathways, and it is important to integrate all of them. However, our results suggest that [one consider] calcium levels as a risk factor for the development of T2D [as] an additional tool for clinicians in the management of the population at risk."

The authors' conclusion should be borne in mind by practitioners involved in case management of individuals with indications of insulin resistance commonly associated with cardiovascular and type 2 diabetes risk:

"An increase in serum calcium concentrations is associated with an increased risk of type 2 diabetes in individuals at high cardiovascular risk."