This study will determine whether an intensive fasting protocol alters hemoglobin A1c measurements or other markers of metabolic and cardiovascular risk by performing a 5-week clinical trial of fasting among 12 pre-diabetic individuals or diabetics whose disease is controlled by diet. Participants will undergo a 5-week intervention of once-per-week 24-hour water-only fasting, including at baseline and at the end of the week for each week of the study (a total of 6 24-hour fasts).

Inclusion Criteria:

1. Male or non-pregnant female, ≥30 and <70 years of age.

2. Ability to understand and sign a written informed consent form, which must be obtained prior to initiation of any study procedures.

3. Prior evidence of pre-diabetic state, with one of the following:

   1. Pre-diabetic with a measured hemoglobin A1c (HbA1c) ≥6.0% or fasting glucose >100 mg/dL without a clinical diabetes diagnosis
   2. Clinically-diagnosed type II diabetic with HbA1c ≥6.0% or fasting glucose ≥110 mg/dL and whose disease is controlled by diet alone.

4. Evidence of metabolic syndrome by having at least 3 of the following 5 criteria:

   1. Fasting glucose level >100 mg/dL.
   2. Blood pressure ≥135 mmHg systolic or ≥85 mmHg diastolic, or use of an antihypertensive medication.
   3. High-density lipoprotein cholesterol <40 mg/dL in males or <50 mg/dL in females.
   4. Triglycerides ≥150 mg/dL or use of a cholesterol-lowering medication.
   5. Waist circumference >40 inches (102 cm) for males or >35 inches (88 cm) for females (or body mass index >25 kg/m2).

Exclusion Criteria:

1. Pregnant and/or lactating women and women of child bearing potential who are not using acceptable means of contraception. Women of childbearing potential must be using adequate measures of contraception (as determined by the Principal Investigator) to avoid pregnancy and should be highly unlikely to conceive during the study period. Women of childbearing potential must have a negative pregnancy test at screen.
2. Diabetics taking any of the following anti-diabetic medications: insulin, metformin, thiazolidinediones, sulfonylureas, alpha-glucosidase inhibitors, meglitinides, or incretins.
3. Prior experience with fasting more than once per month (for 20 hours or more), on average during the last year.
4. Very low body mass index (BMI) (<18.5 kg/m2) or high BMI (>40 kg/m2).
5. Individuals who are nutritionally compromised, as assessed by the Principal Investigator.
6. Any immunodeficiency or prior solid organ transplantation or renal disease.
7. Participation in any other clinical trials involving investigational or marketed products within 30 days prior to entry in the study.
8. Other conditions that in the opinion of the Principal Investigator may increase risk to the subject and/or compromise the quality of the clinical trial.

6 weeks