C-Carbs: A CGM-guided Approach to Teaching Carb Awareness

The C-CARBS study is a randomized controlled study evaluating a patient-facing education program designed to help adults with diabetes use continuous glucose monitoring (CGM) data to guide mealtime insulin dosing. The study focuses on adults with diabetes who use CGM and multiple daily insulin injections (MDI) and who do not routinely use carbohydrate counting or have difficulty with carbohydrate counting.

Participants will be randomly assigned to either the C-CARBS intervention or usual care. Participants assigned to the intervention will receive four weekly, one-hour education sessions with a Certified Diabetes Care and Education Specialist. The sessions will focus on using CGM information, including current glucose levels and glucose trends, to support mealtime insulin dosing without relying solely on traditional carbohydrate counting.

Participants in both groups will complete study assessments throughout the study, including questionnaires and four 3-day meal and insulin logs. Meal and insulin information may be recorded manually or through the participant's Dexcom app. CGM data and laboratory measures, including hemoglobin A1c (HbA1c), will be collected to evaluate changes in glycemic outcomes. The study will also assess participants' insulin dosing behaviors, use of diabetes technology, and experience with the intervention.

The primary goal of the study is to determine whether the C-CARBS education program can improve mealtime insulin dosing behaviors and glycemic outcomes among adults with diabetes who do not routinely use carbohydrate counting.

Inclusion criteria

• Adults 18 years of age or older.
• Diagnosis of diabetes for at least 1 year.
• Currently using or willing to start using a continuous glucose monitor (CGM).
• Currently using multiple daily insulin injections (MDI).
• HbA1c ≥8% at screening/baseline.
• Does not routinely use carbohydrate counting or demonstrates poor/inconsistent carbohydrate counting for mealtime insulin dosing.
• Able and willing to participate in the study visits and intervention sessions.
• Able to provide informed consent.

Exclusion criteria

• Use of an insulin pump or automated insulin delivery system.
• Significant medical, cognitive, or psychiatric condition that, in the investigator's judgment, would interfere with participation or completion of study procedures.

Limited life expectancy that would prevent completion of the study.

• Pregnancy or plans to become pregnant during the study period.
• Current participation in another interventional study that could affect diabetes management or study outcomes.
• Inability/unwillingess to independently use a CGM device or administer insulin.
• Any other condition that, in the investigator's judgment, would make participation inappropriate or interfere with the study's objectives.