Examining the Effects of Diet on Health in Prediabetes With an Online Program

Individuals with prediabetes will be assigned to the treatment group. Classes will occur
online. Participants will be evaluated at 0, 8, and 16 weeks. Our main outcome of interest
is HbA1c (glycated hemoglobin, a measure indicative of blood glucose levels and tied to
diabetes severity) at 16 weeks.

- Inclusion criteria

1. Self-reported clinical diagnosis of prediabetes occurring within the past year.

2. Aged 18 years old and older

3. Per the Centers for Disease Control and Prevention Diabetes Prevention
Recognition Program have a self-reported body mass index (BMI) of ≥ 24 kg/m2 (≥
22 kg/m2 if Asian).

4. Willing and able to participate in the intervention such as having sufficient
control over their food intake. Must have the ability to make choices about the
food they eat; cannot have a lifestyle in which they eat out most of their
meals.)

- Exclusion criteria

1. Unable to provide informed consent.

2. Non English speaker. The intervention groups are conducted in English.

3. No current use of insulin, no immediate plans to start or increase diabetic
mediations, and no use of diabetes medications besides metformin. Insulin and
other diabetes medications other than metformin can alter the safety of the
diets, so to ensure greater safety, we will exclude diabetics using insulin or
medications besides metformin.

4. A substance abuse, mental health, or medical condition that, in the opinion of
investigators, will make it difficult for the potential participant to
participate in the intervention. Such conditions may include: cancer, liver
failure, unstable coronary artery disease, severe emphysema, binge eating
disorder or history of binge eating disorder, bulimia or strong history of
bulimia.

5. Previous use or recent changes in medications that can interfere with the
measures used in the study: current use of insulin; use of systemic (oral or IV)
corticosteroids in the 1 month prior to enrollment or severe autoimmune
disorders or other conditions (e.g. rheumatoid arthritis, lupus), that are
likely to require these medications; and initiation of new class of psychiatric
medications in past 2 months. Such medications can alter measures used in our
research, such as assessments of markers of inflammation, or negatively
influence the safety of the diets.

6. Pregnant or planning to get pregnant in the next 12 months, breastfeeding or
less than 6 months post-partum. The intervention is not designed for the
particular diet considerations during pregnancy and breast-feeding.

7. Current use of weight loss medications or supplements such as Alli or
amphetamine-based drugs that are believed to have some effect on weight. Use of
weight loss aids by potential participants will be reviewed by a core study team
to determine whether participant would be eligible if they stop using the
substance.

8. History of or planned weight loss surgery. The intervention is not designed to
address either the often substantial food intake limits that often result from
weight loss surgery or the significantly disordered eating that people who fail
this extreme intervention may have.

9. Vegan or vegetarian. The intervention diets are more challenging for vegan and
vegetarian participants.

10. No or very limited internet access at a computer. Must be able to complete the
online assessments and access the online class materials.