Serum Calcium Predicts Type 2 Diabetes Development

Miriam E. Tucker

August 22, 2014

Increased serum calcium levels independently predict the risk for type 2 diabetes, a new analysis from the ongoing Prevención Dieta Mediterránea (PREDIMED) study suggests.

The results were published online August 19 in Diabetes Care by dietician and predoctoral student Nerea Becerra-Tomás, of the Institute of Health Carlos III, Madrid, Spain, and colleagues.

"Fasting glucose is, at the moment, the main risk factor for type 2 diabetes, and the diagnosis is based on it. However, after adjusting for glucose, our results demonstrated a role for serum calcium independent of glucose....Measurement [of serum calcium] could add significance to measurement of fasting glucose," study coauthor Mònica Bulló, PhD, professor in the faculty of medicine and health sciences at the Universitat Rovira i Virgili, Reus, Spain, told Medscape Medical News.

Calcium appears to play important roles in both insulin secretion and insulin action, and previous studies have linked elevated calcium levels with higher blood glucose levels and reduced insulin sensitivity. Although some of these data have conflicted, previous prospective studies have shown that elevated serum concentrations are associated with an increased risk of developing type 2 diabetes, the authors write.

The PREDIMED study enrolled 7447 men (aged 55 to 80 years) and women (aged 60 to 80 years) who were at high cardiovascular risk by virtue of either having type 2 diabetes or 3 other cardiovascular risk factors, including family history, overweight/obesity, smoking, hypertension, and dyslipidemia.

The current analysis included 707 of the individuals who did not have diabetes at baseline. In a median follow-up of 4.8 years, 77 of them were diagnosed with diabetes. Mean baseline albumin-adjusted serum calcium was significantly higher for those who developed diabetes than for those who did not (9.74 vs 9.60 mg/dL, P = .023).

After adjustment for potential confounders and exclusion of a total of 57 patients who either developed diabetes before the first 6 months of follow-up or for whom serum calcium data were missing, the risk of developing diabetes for those in the highest serum calcium tertile (mean, 10.2 mg/dL) was more than 3 times greater than for the lowest tertile (9.0 mg/dL), with a hazard ratio of 3.48 (P for trend < .01).

In a model that included adjustment for baseline fasting plasma blood glucose, the hazard ratio was 3.52 for every 1-mg/dL increase in albumin-adjusted serum calcium (P = .02). The results remained significant after adjustment for baseline calcium intake and changes in calcium consumption during follow-up and after exclusion of individuals who were taking calcium and/or vitamin-D supplements.

Dr. Bulló told Medscape Medical News, "Calcium homeostasis is not simple at all, and our results have to be interpreted with caution. 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 type 2 diabetes [as] an additional tool for clinicians in the management of the population at risk."

She noted that the results were obtained in a specific population, and the extent to which they can be extrapolated is not known. "More studies are needed to confirm them to design further prevention strategies....The knowledge in the field of type 2 diabetes is changing day by day, and researchers and clinicians have to pay attention to the new findings in order to improve the patient's care."

This study was funded in part by the Spanish Ministry of Health. The authors have disclosed no relevant financial relationships.

Diabetes Care. Published online August 19, 2014. Abstract


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