The Effect of a Low-fat Vegan Dietary Intervention on Intracellular Lipid, Insulin Sensitivity, and Glycemic Control in Type 2 Diabetes

The goal of this 16-week clinical trial is to assess the health benefits of a low-fat vegan diet on insulin sensitivity and glycemic control in type 2 diabetes. Participants will receive at no cost, study-related weekly nutrition education classes and one-on-one consultation with a registered dietitian.

This study tests the hypothesis that fat content in muscle and liver cells will be reduced and changes in insulin sensitivity will be observed in response to a low-fat vegan diet intervention.

The study will be carried out online (via Zoom or a similar platform). Participants will be asked to attend weekly online classes on nutrition and health.

The study will also require in-person meetings. Participants will travel to the Physicians Committee of Responsible Medicine, Washington, DC, at the beginning of the study (week 0) and the end of the study (week 16) to complete bloodwork (comprehensive metabolic panel, lipid panel, and HbA1c) and several medical tests (standard meal test, indirect calorimetry, dual-energy x-ray absorptiometry \[DEXA Scan, an imaging test that measures changes in bone mineral density/bone strength\], and Advanced Glycation End-products measurement). They will also need to travel to the Magnetic Research Center at Yale University School of Medicine, New Haven, CT at the beginning of the study (week 0) and the end of the study (week 16) to have a Magnetic Resonance (MR) spectroscopy to quantify liver and muscle fat content.

Eligibility Criteria:
Inclusion Criteria:

1. Men and women with type 2 diabetes treated by diet and/or oral hypoglycemic agents other than sulfonylureas
2. Age ≥18 years
3. Body mass index 26-40 kg/m2
4. Medications (antidiabetic, antihypertensive, and lipid-lowering) have been stable for the past 3 months
5. HbA1c between 6.0-10.5% (42-91 mmol/mol)

Exclusion Criteria:

1. Diabetes mellitus, type 1 and/or treatment with insulin or sulfonylureas
2. Metal implants, such as a cardiac pacemaker or an aneurysm clip
3. History of any endocrine condition that would affect body weight, such as thyroid disease, pituitary abnormality, or Cushing's syndrome
4. Smoking during the past six months
5. Alcohol consumption of more than 2 drinks per day or the equivalent, episodic increased drinking (e.g., more than 2 drinks per day on weekends), or a history of alcohol abuse or dependency followed by any current use
6. Use of recreational drugs in the past 6 months
7. Use within the preceding six months of medications that affect appetite or body weight, such as estrogens or other hormones, thyroid medications, systemic steroids, antidepressants (tricyclics, monoamine oxidase inhibitors, selective serotonin reuptake inhibitors), antipsychotics, lithium, anticonvulsants, appetite suppressants or other weight-loss drugs, herbs for weight loss or mood, St. John's wort, ephedra, beta-blockers
8. Pregnancy or intention to become pregnant during the study period
9. Unstable medical or psychiatric illness
10. Evidence of an eating disorder
11. Likely to be disruptive in group sessions
12. Already following a low-fat, vegan diet
13. Lack of English fluency
14. Inability to maintain current medication regimen
15. Inability or unwillingness to participate in all components of the study
16. Intention to follow another weight-loss method during the trial