Efficacy and Safety of a Ketogenic Diet in Type 1 Diabetes

Inclusion 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 forthe duration of the study, if using a different sensor, to reduce variability inglucose values associated with different CGM products

• Use of cellular phone with data capability for wireless connectivity to the CGMsystem.

Exclusion Criteria:

• 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 severehypoglycemia) 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 planningto 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, orcardiovascular 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 riskof 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 anyreason, the research team considers an inappropriate candidate for the study.