ABSTRACT Type 2 diabetes is the most expensive chronic disease in the U.S. Nutritional management of type 2 diabetes has the potential to improve glycemic control and clinical outcomes with fewer side effects and lower costs than intensive medical management. However, we are far from fully realizing the potential of nutritional management to improve diabetes outcomes. One important limitation is the lack of high-quality research. Last year, the American Diabetes Association’s (ADA’s) Nutrition Review Committee (on which the PI served) concluded that: “Despite widespread interest in evidence-based diabetes nutrition therapy interventions, large, well-conducted nutrition trials continue to lag far behind other areas of diabetes research.” This proposal addresses critical gaps in our knowledge to inform clinical guidelines for the nutritional management of type 2 diabetes in regard to macronutrient content. Some evidence indicates that reducing overall carbohydrate intake with a very low-carbohydrate eating plan can improve glycemic control compared to eating plans with greater carbohydrate content. However, critical knowledge gaps prevent clear recommendations: 1) a gap in knowledge about the durability of gains in glycemic control, 2) concerns about possible long-term adverse effects, and, 3) although current recommendations suggest individualizing recommendations about carbohydrate content, we have almost no knowledge to guide this. To address these gaps, we propose a two- site, parallel-group, randomized (1:1) trial with a 12-month follow-up in 180 adults with type 2 diabetes, comparing a very low-carbohydrate diet to a moderate-carbohydrate plate-method diet—both are approaches recommended by the ADA. Both groups will be taught previously tested behavioral strategies to maintain adherence to nutritional treatment. Aim 1: Compare the long-term effects of the two diets on measures of physical health: glycemic control (HbA1c, primary outcome), weight, inflammation (C-reactive protein), ability to reduce the use of diabetes medications and medication-related costs, and diabetes-related distress over 12 months. We hypothesize that the very low-carbohydrate diet group (as compared to the moderate- carbohydrate diet group) will have lower HbA1c and improvements in other outcomes at 12 months. Aim 2: Compare adverse effects. Aim 3: Assess factors that identify individuals who will particularly benefit from one of the nutritional intervention arms, including insulin resistance, body mass index, and sex. The proposed study will address important gaps in the evidence base for the nutritional management of type 2 diabetes and has the potential to strengthen evidence-based approaches to improve type 2 diabetes outcomes.