The proposed study is a randomized controlled, pilot effectiveness trial comparing the LoBAG diet to a control diet in 38 participants with DM2 over 12 weeks. Participants will have DM2 that is not under ideal glycemic control (HgbA1c 7.0-9.5%) and must be taking no glycemic medications or metformin. Participants will be free-living (given diet instruction and dietitian support, but asked to prepare meals in their own homes). The primary endpoint will be HgbA1c, measured at baseline and at the end of the 12-week diet intervention. Additional outcome measures will include: weight, fasting plasma glucose, fasting serum insulin, postprandial plasma glucose and serum insulin following a test meal consistent with the assigned diet, serum fructosamine, fasting serum lipids, stool samples for gut microbiome analysis, and surveys to assess quality of life, including the Diabetes Treatment Satisfaction Questionnaire. Compliance outcomes will include: urine nitrogen to creatinine ratio, survey data, three-day food diaries, and unannounced 24-hour diet recalls.

Thirty-eight adult men and women with DM2 will be recruited from the University of Minnesota and surrounding communities, and will be randomized to treatment with the LoBAG diet or a control diet. Following a consent and screening visit, there will be 5 additional study visits over a 12-week diet intervention period. Instruction in the assigned diet will be provided by a research dietitian at the beginning of the 12-week period, and reinforced at subsequent visits throughout the study. Participants will be asked to purchase food, prepare food, and consume the assigned diet in their own homes. They will be asked to keep activity level constant and to continue medications for diabetes (metformin or no medication) without change during the intervention. The primary outcome, HgbA1c, and secondary outcome measures will be assessed at baseline and following diet intervention. Study visits will occur at baseline (visits 1 and 2), week 1 (visit 3), week 6 (visit 4), week 9 (visit 5) and week 12 (final study visit). In addition to scheduled study visits the research team will contact participants every other week by telephone to address any issues that arise, with the purpose of increasing compliance and retention. Participants will be contacted once in weeks 9-12 for a 24-hour diet recall collected by the Nutrition Coordinating Center at the University of Minnesota. Study procedures will conclude after the 12-week diet intervention period and collection of all outcome measures.

Inclusion Criteria:

• 18 years of age or older
• Diagnosis of type 2 diabetes mellitus
• Hemoglobin A1c of 7.0-9.5%
• Taking no medications for diabetes or taking metformin

Exclusion Criteria:

• Type 1 diabetes mellitus
• Treatment with insulin
• BMI < 27 kg/m^2
• Change in weight of more than 5 pounds in the prior 3 months
• Estimated glomerular filtration rate (GFR) < 60 ml/minute/1.73 m^2
• Urine albumin > 300 mg/g creatinine
• Anemia
• Pregnancy or immediate plans to become pregnant
• Current breast feeding
• Use of antibiotics in the 3 month period prior to study enrollment
• Dietary restriction(s) that would preclude consumption of the study diets
• Inability or unwillingness to prepare meals
• Presence of any disease which would make adherence to the study protocol difficult

12 weeks