This study aims to test a dietary intervention for diabetes in a medical practice setting, with the aim of developing a model for diabetes care that can be used widely. The investigators hypothesize that a low-fat vegan diet will be effective for management of diabetes and will be feasible in a practice-based setting.

Specific Aim 1 tests the hypothesis that the nutrition intervention (low fat, low-GI vegan diet) improves glycemic control, body weight, plasma lipid concentrations, blood pressure, and indices of renal function in a within-group analysis.

Specific Aim 2 tests the hypothesis that the nutrition intervention (low fat, low-GI vegan diet) is more effective than standard nutrition care for improving glycemic control, body weight, plasma lipid concentrations, blood pressure, and indices of renal function in individuals with type 2 diabetes

Specific Aim 3 tests the hypothesis that a low-fat vegan diet is sustainable among individuals with type 2 diabetes for a 20-week period, with weekly classes, and in a follow-up period of one year with limited professional support.

Specific Aim 4 tests the hypothesis that a low-fat vegan diet has an acceptability that is comparable to that of standard nutrition care among individuals with type 2 diabetes.

Specific Aim 5 tests the hypothesis that the effects of the dietary interventions on A1c and body weight are reduced in individuals with the A1 allele of the Taq1A and Taq1B polymorphism

Inclusion Criteria:

1. a diagnosis of type 2 diabetes mellitus, as defined by a fasting plasma glucose concentration ≥126 mg/dl on 2 occasions or a prior physician's diagnosis of type 2 diabetes with the use of hypoglycemic medications for at least 6 months
2. male or female
3. A1c between 6.5% and 10.5%
4. age at least 18 years
5. ability and willingness to participate in all components of the study
6. willingness to be assigned to either a low-fat, vegan diet or to standard nutrition care
7. diabetes medications unchanged for 1 month prior to volunteering for the study
8. patient of Dr. Mark Sklar

Exclusion Criteria:

1. body mass index >45 kg/m2
2. 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
3. use of recreational drugs in the past 6 months (past drug use, if fully recovered, is not a criteria for exclusion)
4. pregnancy or plans to become pregnant
5. history of severe mental illness (with current unstable status)
6. likely to be disruptive in group sessions (as determined by research staff)
7. Signs/symptoms of acute uncontrolled diabetes (including but not limited to polyuria, polydipsia, blurred vision, uncontrolled weight loss)
8. unstable medical status
9. already following a low-fat, vegetarian diet
10. an inordinate fear of blood draws
11. inability to maintain current medication regimen
12. lack of English fluency