Why is this study being conducted?
Despite technological advances, glucose control remains suboptimal in people with type 1 diabetes. Diet plays an important role in diabetes management, and some foods have a bigger effect on blood glucose than others. This study will help us understand the effect of dietary carbohydrate on blood glucose control and brain function in people with type 1 diabetes, and evaluate the effects and safety of a very low carbohydrate compared to a standard diet.
What will I be asked to do?
You will receive free food deliveries throughout the study and will be asked to eat only the foods provided for 12 weeks.
You will be asked to upload and share data from your diabetes devices (CGM, insulin pump) to a cloud-based software and have a weekly check-in with the study team. You will be asked to use a wrist-wearable activity monitor to quantify exercise.
The study involves up to five in-person visits at Boston Children’s Hospital or Beth Israel Deaconess Medical Center. You will be asked to arrive in the morning fasted (without eating) on a weekday during some of these visits.
Three of the visits, including the screening visit, take about one to two hours and will involve a blood draw. One visit will be a brief MRI scan. Two longer visits take four to five hours and will involve IV placements, frequent blood draws, and a glucagon injection or ketone drink, as well as MRI studies of your brain during hypoglycemia. You will receive IV insulin to drop your blood glucose level to 50 to 60 mg/dL for up to 30 minutes.
Who is eligible?
Males and females aged 18-40 with:
- type 1 diabetes for at least 1 year
- BMI between 18.5-35 kg/m2
- stable glycemic control (HbA1c = 6.5-9%)
- current use of a CGM and insulin pump
- attendance of at least one diabetes care visit in the past year (including virtual)
Conditions that prohibit participation:
- diabetic ketoacidosis (DKA) or hypoglycemia with seizure or coma in the past six months
- dietary restrictions or intolerances that are incompatible with planned food deliveries (e.g., celiac disease, gastroparesis, some allergies)
- following a weight loss or otherwise restrictive diet
- vigorous exercise for >2 hours on >3 days/week
- history of an eating disorder or at risk
- major medical illness or use of certain medications other than insulin and metformin that could interfere with metabolic or glycemic variables
- significant psychiatric illness
- smoking, use of recreational drugs, or excessive alcohol consumption
- pregnancy or breastfeeding
- for participants who undergo MRI: standard MRI exclusion criteria; irregular menses; use of psychotropic medication that cannot be safely held for MRI image acquisition
Are there any risks associated with participating?
Symptoms such as fatigue, cramps, and constipation may occur when switching to a very low carbohydrate diet. Possible risks include hypoglycemia or elevated ketone levels while following the very low carbohydrate diet or from the ketone drinks. You may feel nauseous from the glucagon medication or ketone drink. There is a small chance of allergic reaction from the delivered meals or study medications (glucagon, oral ketones). You may experience slight pain or bruising from the blood draws and a feeling of claustrophobia (fear of small places) during the MRI.
What are the benefits of participation?
- You will receive free meals, reimbursement for parking and transportation, and financial compensation of up to $1,300.
- You will receive intensive diabetes management and education.
Are there other things I should know?
Participating in research is voluntary and separate from your clinical care. You may decline participation or start the study and choose to drop out at any time. All research data are kept confidential.
More detailed study information
- After the initial screening visit, there will be an individual or group visit during which you will have a fasting blood draw, be randomized into one of the two diets, and receive diet education and a refresher on diabetes management skills. This visit should take roughly two hours.
- Each weekly check-in thereafter will be individual and about 30 minutes each. Most of the check-ins will be completed virtually via Zoom. We will collaboratively review your blood glucose and insulin data, and may decide to make adjustments to your insulin regimen. At the end of the study, you will come in to Boston Children’s Hospital or Beth Israel Deaconess Medical Center in the morning after a 10-hour fast, and we will take a small sample of blood.
- All participants will also come in for a brief MRI scan.
- In addition, during the study, you will participate in two four to five hour metabolic visits to evaluate your hypoglycemia response. We will place two IV catheters, one to give insulin and one to check your blood glucose and other labs every five to 30 minutes. We will slowly drop your blood glucose level to 50-60 mg/dL and keep it there safely. A physician will be with you at all times, and we will have IV glucose to treat you quickly if your blood glucose level drops too low or you become too uncomfortable. Depending on the visit, you will receive a glucagon injection, drink a ketone beverage, and/or have a brain MRI to evaluate brain function during hypoglycemia.
- Food will be delivered weekly to your home address (3 meals and 1 to 2 snacks per day).
- You will be asked to eat only the foods that are provided to you by the study.
- You will be asked to maintain your current level of physical activity.
- You will be asked to wear an activity monitor on your wrist to quantify physical activity.
- You will be asked to complete a brief daily online questionnaire on hunger, hypoglycemic episodes, physical activity, etc.
- You will be asked to upload your diabetes devices once each week to Tidepool, a diabetes data management software, and have a weekly check-in with the study team.
- You will need to call the study team to reschedule if you are unable to make your scheduled study visit.
- All of your meals will be provided by a meal delivery service. We will also provide snacks via mail or at in-person visits.
- There is no cost to you for any food during the study.
Interested in participating? Have further questions?
You may also find answers to your questions on our FAQ page.