Obesity, and its metabolic consequences - impaired fasting glucose (IFG) and diabetes, is highly prevalent among Arab women in Israel and the Middle East. Since life style modification is difficult to achieve in this population it is important to assess whether other modifiable risk factors can be detected. There is evidence that the homeostasis of vitamin D has a significant role in the eventual development of diabetes. Previous cross sectional studies have shown that low 25 (OH) vitamin D levels are related to glucose intolerance, diabetes, insulin resistance and metabolic syndrome. The study hypothesis is that 25(OH) vitamin D deficiency is highly prevalent among Arab women with IFG and that vitamin D supplementation may improve IFG and by that reduce the risk for future overt diabetes. Additionally, obesity is associated with a low-grade inflammation of white adipose tissue (WAT) resulting from chronic activation of the innate immune system. In obesity, there is an increased production and secretion of a wide range of inflammatory molecules including interleukin-10 (IL-10), which may have systemic effects on WAT and other organs. To that end the investigators will assess the influence of vitamin D supplementation on IL-10 and hs-CRP.

Eligible women will be invited by their primary care physician to participate in the study. After signing an informed consent women will be randomized to receive oral vitamin D 100,000 IU or similar placebo once a month for three consecutive months. Pertinent clinical and demographic date will be documented and relevant laboratory test will be performed by the primary care team. One month after the third dose the same data and tests will be retrieved on each woman. Compliance with the study protocol will be enhanced and confirmed by a research assistant.

Objectives:

To assess the relationship between IFG and 25(OH) vitamin D levels in overweight Arab women.

To assess whether vitamin D supplementation significantly improves IFG. To assess whether vitamin D supplementation significantly modifies IL-10 and hs-CRP.

Inclusion Criteria:

• Arab women, age 40-65
• No significant handicap or disabilities in ADL
• BMI > 25 kg/m2
• IFG of 100-125 mg/dl

Exclusion Criteria:

• Diabetes Mellitus
• Other medical conditions that may have an effect on IFG (cancer, chronic renal failure, inflammatory diseases etc)
• History of vascular disease
• Regular use of medications that may affect IFG (steroids, HRT, diuretics etc)
• Hypercalcemia (albumin corrected Ca >10.3 mg/dl)
• Inability to sign an informed consent due to mental or psychiatric ailment