Calcium plus vitamin D supplementation and the risk of incident diabetes in the Women's Health Initiative
Ian H de Boer, Lesley F Tinker, Stephanie Connelly, J David Curb, Barbara V Howard, Bryan Kestenbaum, Joseph C Larson, JoAnn E Manson, Karen L Margolis, David S Siscovick, Noel S Weiss, Women's Health Initiative Investigators, Elizabeth Nabel, Jacques Rossouw, Shari Ludlam, Linda Pottern, Joan McGowan, Leslie Ford, Nancy Geller, Ross Prentice, Garnet Anderson, Andrea LaCroix, Charles L Kooperberg, Ruth E Patterson, Anne McTiernan, Sally Shumaker, Evan Stein, Steven Cummings, Sylvia Wassertheil-Smoller, Aleksandar Rajkovic, Annlouise R Assaf, Lawrence Phillips, Shirley Beresford, Judith Hsia, Rowan Chlebowski, Evelyn Whitlock, Bette Caan, Jane Morley Kotchen, Linda Van Horn, Henry Black, Marcia L Stefanick, Dorothy Lane, Rebecca Jackson, Cora E Lewis, Tamsen Bassford, Jean Wactawski-Wende, John Robbins, F Allan Hubbell, Lauren Nathan, Robert D Langer, Margery Gass, Marian Limacher, Robert Wallace, Judith Ockene, Norman Lasser, Mary Jo O'Sullivan, Robert Brunner, Gerardo Heiss, Lewis Kuller, Karen C Johnson, Robert Brzyski, Gloria E Sarto, Denise Bonds, Susan Hendrix, Ian H de Boer, Lesley F Tinker, Stephanie Connelly, J David Curb, Barbara V Howard, Bryan Kestenbaum, Joseph C Larson, JoAnn E Manson, Karen L Margolis, David S Siscovick, Noel S Weiss, Women's Health Initiative Investigators, Elizabeth Nabel, Jacques Rossouw, Shari Ludlam, Linda Pottern, Joan McGowan, Leslie Ford, Nancy Geller, Ross Prentice, Garnet Anderson, Andrea LaCroix, Charles L Kooperberg, Ruth E Patterson, Anne McTiernan, Sally Shumaker, Evan Stein, Steven Cummings, Sylvia Wassertheil-Smoller, Aleksandar Rajkovic, Annlouise R Assaf, Lawrence Phillips, Shirley Beresford, Judith Hsia, Rowan Chlebowski, Evelyn Whitlock, Bette Caan, Jane Morley Kotchen, Linda Van Horn, Henry Black, Marcia L Stefanick, Dorothy Lane, Rebecca Jackson, Cora E Lewis, Tamsen Bassford, Jean Wactawski-Wende, John Robbins, F Allan Hubbell, Lauren Nathan, Robert D Langer, Margery Gass, Marian Limacher, Robert Wallace, Judith Ockene, Norman Lasser, Mary Jo O'Sullivan, Robert Brunner, Gerardo Heiss, Lewis Kuller, Karen C Johnson, Robert Brzyski, Gloria E Sarto, Denise Bonds, Susan Hendrix
Abstract
Objective: Experimental and epidemiologic studies suggest that calcium and vitamin D may reduce the risk of developing diabetes. We examined the effect of calcium plus vitamin D supplementation on the incidence of drug-treated diabetes in postmenopausal women.
Research design and methods: The Women's Health Initiative Calcium/Vitamin D Trial randomly assigned postmenopausal women to receive 1,000 mg elemental calcium plus 400 IU of vitamin D3 daily, or placebo, in a double-blind fashion. Among 33,951 participants without self-reported diabetes at baseline, we ascertained by treatment assignment new diagnoses of diabetes treated with oral hypoglycemic agents or insulin. Effects of the intervention on fasting measurements of glucose, insulin, and insulin resistance were examined among a subset of participants.
Results: Over a median follow-up time of 7 years, 2,291 women were newly diagnosed with diabetes. The hazard ratio for incident diabetes associated with calcium/vitamin D treatment was 1.01 (95% CI 0.94-1.10) based on intention to treat. This null result was robust in subgroup analyses, efficacy analyses accounting for nonadherence, and analyses examining change in laboratory measurements.
Conclusions: Calcium plus vitamin D3 supplementation did not reduce the risk of developing diabetes over 7 years of follow-up in this randomized placebo-controlled trial. Higher doses of vitamin D may be required to affect diabetes risk, and/or associations of calcium and vitamin D intake with improved glucose metabolism observed in nonrandomized studies may be the result of confounding or of other components of foods containing these nutrients.
Trial registration: ClinicalTrials.gov NCT00000611.
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Source: PubMed