Vitamin D 20 000 IU per Week for Five Years Does Not Prevent Progression From Prediabetes to Diabetes

• Published in: The journal of clinical endocrinology and metabolism Vol. 101; no. 4; pp. 1647 - 1655
• Main Authors: Jorde, Rolf, Sollid, Stina T., Svartberg, Johan, Schirmer, Henrik, Joakimsen, Ragnar M., Njølstad, Inger, Fuskevåg, Ole M., Figenschau, Yngve, Hutchinson, Moira Y. S.
• Format: Journal Article
• Language: English
• Published: United States Oxford University Press 01.04.2016; Copyright by The Endocrine Society
• Subjects: 25-Hydroxyvitamin D; Blood Glucose - metabolism; Blood pressure; Diabetes; Diabetes mellitus (non-insulin dependent); Diabetes Mellitus, Type 2 - etiology; Diabetes Mellitus, Type 2 - metabolism; Diabetes Mellitus, Type 2 - prevention & control; Dietary Supplements; Female; Glucose; Glucose tolerance; Glucose Tolerance Test; Glycated Hemoglobin A - metabolism; Humans; Insulin Resistance; Lipids; Male; Middle Aged; Placebos; Prediabetic State - complications; Serum lipids; Vitamin D; Vitamin D - administration & dosage; Vitamin D - analogs & derivatives; Vitamin D Deficiency - physiopathology; Vitamin deficiency; Vitamins - administration & dosage
• ISSN: 0021-972X; 1945-7197
• DOI: 10.1210/jc.2015-4013

Context:Vitamin D deficiency is associated with insulin resistance and risk of future diabetes.Objective:The objective of the study was to test whether supplementation with vitamin D to subjects with prediabetes will prevent progression to type 2 diabetes mellitus (T2DM).Design:This was a randomized controlled trial performed in 2008 through 2015.Setting:The study was conducted at the clinical research unit at a teaching hospital.Patients:Five hundred eleven subjects (mean age 62 y, 314 males) with prediabetes diagnosed with an oral glucose tolerance test as part of the Tromsø Study 2007–2008 were included. A total of 256 were randomized to vitamin D and 255 to placebo. Twenty-nine subjects in the vitamin D and 24 in the placebo group withdrew because of adverse events.Interventions:Interventions included vitamin D (cholecalciferol) 20 000 IU/wk vs placebo for 5 years. Annual oral glucose tolerance tests were performed.Main Outcome Measure:Progression to T2DM was the main outcome measure. Secondary outcomes were change in glucose levels, insulin resistance, serum lipids, and blood pressure.Results:The mean baseline serum 25-hydroxyvitamin D level was 60 nmol/L (24 ng/mL). One hundred three in the vitamin D and 112 in the placebo group developed T2DM (hazard risk 0.90; 95% confidence interval 0.69–1.18, Cox regression, P = .45, intention to treat analysis). No consistent significant effects on the other outcomes were seen. Subgroup analyses in subjects with low baseline 25-hydroxyvitamin D yielded similar results. No serious side effects related to the intervention were recorded.Conclusions:In subjects without vitamin D deficiency, vitamin D supplementation is unlikely to prevent progression from prediabetes to diabetes. Very large studies with inclusion of vitamin D-deficient subjects will probably be needed to show such a putative effect.