Efficacy and Safety of a Ketogenic Diet in Type 1 Diabetes

Eligibility Criteria

• * Age ≥18 and ≤65 years
• * T1D diagnosed \>1 year prior to screening
• * HbA1c 7.0%-9.0%
• * Stable insulin delivery method for the past 30 days
• * Ability to read all device instructions and insulin pump settings
• * eGFR ≥60 mL/min/1.73 m2
• * Use of an insulin pump or insulin delivery by multiple daily injections
• * Use of personal CGM for at least 12 weeks and willing to change to Dexcom CGM for the duration of the study, if using a different sensor, to reduce variability in glucose values associated with different CGM products
• * Use of cellular phone with data capability for wireless connectivity to the CGM system.
• * Body mass index \<20.0 or \>34.9 kg/m2
• * Severe gastroparesis or history of bariatric surgery
• * Diabetes-related hospitalization (including for diabetic ketoacidosis or severe hypoglycemia) within 12 months of screening
• * Poorly controlled hypertension (SBP ≥160 mmHg or DBP ≥100 mmHg)
• * Taking diabetes medications, other than insulin (particularly SGLT2 inhibitors, which are associated with an increased risk of euglycemic DKA)
• * Structured exercise \>210 minutes per week
• * Pregnant, lactating, not using effective birth control if premenopausal, or planning to become pregnant within the 6-month study period
• * Unstable weight (\>4% change in the last 2 months)
• * Significant organ system dysfunction (e.g., severe pulmonary, renal, hepatic, or cardiovascular disease)
• * Anemia (Hgb \<10 g/dL)
• * Major psychiatric illness
• * Active tobacco use (\>8 cigarettes/day) or illegal drug use
• * Regular alcohol consumption (\>10 standard drinks per week)
• * Use of medications known to affect the study outcome measures or increase the risk of study procedures that cannot be temporarily discontinued for this study
• * Familial hypercholesterolemia
• * Active eating disorder
• * Dietary restrictions incompatible with a very-low-carbohydrate KD, vegan diet, vegetarian diet, severe lactose intolerance, severe aversion/sensitivity to eggs, fish, nuts, wheat, or soy, and any anaphylactic food allergy
• * Already consuming a low-carbohydrate (\<130 g/day) diet
• * Persons who are not able to grant voluntary informed consent
• * Persons who are unable or unwilling to follow the study protocol or who, for any reason, the research team considers an inappropriate candidate for the study.