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ARS Home » Northeast Area » Boston, Massachusetts » Jean Mayer Human Nutrition Research Center On Aging » Research » Publications at this Location » Publication #201796
Title: The effects of combined vitamin D and calcium supplementation on glycemia, insulin resistance and systemic inflammation in non-diabetic adults age 65 and older

Author
item PITTAS, ANASTASSIOS - TUFTS-NEMC
item HARRIS, SUSAN - TUFTS/HNRCA
item STARK, PAUL - TUFTS-NEMC
item Dawson-Hughes, Bess

Submitted to: Diabetes Care
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/10/2007
Publication Date: 2/2/2007
Citation: Pittas, A.G., Harris, S.S., Stark, P., Dawson-Hughes, B. 2007. The effects of combined vitamin D and calcium supplementation on glycemia, insulin resistance and systemic inflammation in non-diabetic adults age 65 and older. Diabetes Care. 30(4):980-6.

Interpretive Summary: In a 3-year randomized controlled trial, the effects of combined vitamin D and calcium supplementation vs. placebo on glycemia, insulin sensitivity and systemic inflammation were compared in three hundred and fourteen healthy non-diabetic Caucasian adults age 65 years or older. The experimental group received daily supplements of 700 IU of vitamin D3 and 500 mg of calcium (as citrate malate) while the control group received placebos daily for three years. The results show that in healthy older adults with glucose intolerance, vitamin D and calcium supplementation may reduce increases in glycemia and insulin resistance that occur over time. Thus there is a potential that meeting the requirement for calcium and vitamin D will lower risk of developing Type 2 diabetes.

Technical Abstract: Altered vitamin D and calcium homeostasis may play a role in the development of glucose intolerance and type 2 diabetes. In a 3-year randomized controlled trial, we compared the effects of combined vitamin D and calcium supplementation vs. placebo on glycemia, insulin sensitivity and systemic inflammation in healthy adults 65 years of age or older. Three hundred and fourteen healthy Caucasian older adults without diabetes received either 700 IU of vitamin D3 and 500 mg of calcium (as citrate malate) or placebos daily for three years. Fasting plasma glucose (FPG), insulin sensitiviy estimated by homeostasis model assessment-insulin resistance (HOMA-IR), and plasma C-reactive protein and interleukin-6 were measured before and after the 3-year intervention. The results showed that the effects of combined vitamin D and calcium supplementation on 3-year change in FPG depended on baseline glucose tolerance status (p=0.015 for interaction between treatment group baseline FPG). Therefore, we conducted analyses separately in participants with normal glucose tolerance (FPG,5.6mmol/l [100 mg/dl], n=222) and impaired fasting glucose (IFG:FPG 5.6-6.9 mmol/l [100-125] mg/dl, n=92) at baseline. Among participants with impaired fasting glucose at baseline those who took combined vitamin D-calcium supplements had a significantly lower rise in FPG at 3 years compared to those on placebo (0.02 mmol/L [0.4 mg/dl] vs. 0.91, p=0.033). In the normal glucose tolerance subgroup, there was no difference in the change in FPG or HOMA-IR between the two treatment arms. There were no differences in C-reative protein or interleukin-6 between the two treatment arms in either subgroup. The results indicate that in healthy older adults with glucose intolerance, supplementation with vitamin D and calcium may attenuate increases in glycemia and insulin resistance that occur over time. This study was not designed for the measured outcomes and cannot separate the independent effects of vitamin D and calcium.