Vitamin D and Type 2 Diabetes Study

Inclusion Criteria:

   1. Pre-diabetes ("at increased risk for diabetes") defined by meeting 2-out-of-3 of the
   following glycemic criteria at the baseline visit:

      1. Fasting plasma glucose (FPG) 100-125 mg/dL

      2. 2-hour plasma glucose (2hPG) 140-199 mg/dL

      3. Hemoglobin A1c (HbA1c) 5.7-6.4%

   2. Age ≥ 30 years .(≥25 years for people of the following races: American-Indian, Alaska
   Native, Native Hawaiian or Other Pacific Islander).

   3. Body Mass Index ≥ 24.0 (22.5 for Asians) and ≤ 42.0 kg/m2

   4. Provision of signed and dated written informed consent prior to any study procedures.

Major Exclusion Criteria:

   1. Diabetes based on either of the following criteria:

      1. History (past 1 year) of hypoglycemic pharmacotherapy (oral or injectable
      medication approved by the FDA for type 2 diabetes), used for any condition (e.g.
      pre-diabetes, diabetes, polycystic ovarian syndrome.

      2. Meeting the diagnosis criteria for diabetes

   2. History (past 3 years) of hyperparathyroidism, nephrolithiasis or hypercalcemia.

   3. Pregnancy (past 1 year by report or positive pregnancy test at screening), intent to
   become pregnant in the next 4 years or unprotected intercourse. History of gestational
   diabetes is not an exclusion criterion.

   4. Currently breastfeeding.