Type 1 Diabetes Management Using a Very Low Carbohydrate Versus Standard Diet

Overview

Despite major technological advances, management of type one diabetes mellitus (T1D) remains suboptimal, putting millions of people at risk for immediate and long-term complications. After meals, a mismatch between carbohydrate absorption rate and insulin action typically leads to alternating periods of hyper- and hypoglycemia. A conceptually promising approach to control both problems is dietary carbohydrate restriction to reduce postprandial blood glucose changes and insulin needs. In a prior survey study, the investigators documented exceptional glycemic control (HbA1c 5.67%) and low acute complication rates among 316 children and adults with T1D consuming a very-low-carbohydrate diet. To test the feasibility of this approach, the investigators will conduct a randomized-controlled feeding study involving 32 adults and adolescents with T1D. Participants will be randomized to receive a very low carbohydrate vs. standard carbohydrate diet. Participants will be in the study for 12 weeks and receive all their meals by meal delivery.They will share continuous glucose monitoring data with the study team and be in close communication to adjust insulin doses as needed. All participants will have a screening visit, an individual or group education session, and 3 study visits to evaluate diabetes control and metabolic health. Some of these visits will have a fasting blood draw. Two of the visits will also comprise additional metabolic studies to assess glucagon response and brain function during hypoglycemia by magnetic resonance imaging (MRI). Participants will have IV catheters placed and receive IV insulin to drop blood glucose levels to 50 mg/dl for up to 30 minutes. The primary outcome will be HbA1c change from baseline. Secondary outcomes include detailed measures of glycemic variability, metabolic health, and quality of life.

Interventions

• Other very low carbohydrate diet
  All meals will be delivered and participants will consume study foods exclusively. Participants will receive a fiber supplement as needed with each meal to support digestive health, and a daily multi-vitamin, magnesium and omega-three supplement to ascertain micronutrient sufficiency. Participants will be weighed at each study visit and the diet plan will be adjusted for satiety and weight-maintenance. The diet composition will be as follows: 5% carbohydrate, 70% fat, 20% protein.
• Other standard carbohydrate diet
  All meals will be delivered and participants will consume study foods exclusively. Participants will receive a daily multi-vitamin and omega-3 supplement to ascertain micronutrient sufficiency. Participants will be weighed at each study visit and the diet plan will be adjusted for satiety and weight-maintenance. The diet composition will be as follows: 50% carbohydrate, 30% fat, 20% protein.

Primary outcome measures

• Hemoglobin A1C change [Time frame: 12 weeks - baseline]

Secondary outcome measures (12)

• total daily insulin dose [Time frame: week 0 and 12]
• percent time spent in the glycemic target range of 70-140 mg/dl [Time frame: week 0 and 12]
• percent time spent below the glycemic target of 70 mg/dl [Time frame: week 0 and 12]
• percent time in hypoglycemia below 54 mg/dl [Time frame: week 0 and 12]
• percent time spent above the glycemic target of 140 mg/dl [Time frame: week 0 and 12]
• percent time spent in hyperglycemia [Time frame: week 0 and 12]
• blood glucose average [Time frame: week 0 and 12]
• blood glucose standard deviation [Time frame: week 0 and 12]
• Glycemic Variability Index, a measure for glycemic variability normalized to mean blood glucose level [Time frame: week 0 and 12]
• Mean Amplitude of Glycemic Excursions (MAGE), a measure for postprandial glycemic variability [Time frame: week 0 and 12]
• fasting total cholesterol [Time frame: week 0 and 12]
• fasting high density lipoprotein cholesterol [Time frame: week 0 and 12]

Eligibility criteria

Inclusion criteria

• Males and females with T1D for at least 1 year
• Age 18 to 40 years
• Tanner stage ≥ IV
• BMI 18.5-35 kg/m2
• Stable glycemic control (HbA1c 6.5-9%)
• Use of a continuous glucose monitor (CGM)
• Use of an insulin pump
• Attendance of at least 1 diabetes care visit over the past 12 months (including virtual)

Exclusion criteria

• Ketoacidosis or severe hypoglycemia with seizure or coma in the past 6 months
• Dietary restrictions or intolerances that are incompatible with the planned food deliveries, e.g. celiac disease, gastroparesis, certain food allergies
• Following a weight-loss or otherwise restrictive diet
• Vigorous exercise >2 hours on >3 days a week
• History of an eating disorder or at risk for eating disorder, assessed by the Eating Disorders Diagnostic Scale (EDDS)
• Major medical illness or use of 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
• Anemia
• For participants who undergo MRI:

• Standard MRI exclusion criteria
• Irregular menses
• Use of psychotropic medication other than SSRIs or other mild antidepressant or anxiety medications (unless these medications are safe to be held for several days to allow for the acquisition of MRI data)

Criteria are shown verbatim from the registry (in English). Final eligibility is always assessed by the study center.

Healthy volunteers: No

Study design

Allocation

Randomized

Model

Parallel assignment

Masking

Open label

Primary purpose

Supportive care

Study locations

United States · 1 center

• Boston Children's Hospital — Boston

Publications

• Lennerz BS, Barton A, Bernstein RK, Dikeman RD, Diulus C, Hallberg S, Rhodes ET, Ebbeling CB, Westman EC, Yancy WS Jr, Ludwig DS. Management of Type 1 Diabetes With a Very Low-Carbohydrate Diet. Pediatrics. 2018 Jun;141(6):e20173349. doi: 10.1542/peds.2017-3349. Epub 2018 May 7. PMID 29735574

Identifiers

NCT: NCT03710928 · IRB-P00030039

Primary sources (government registries)

• ClinicalTrials.gov (US NIH)

View this study on ClinicalTrials.gov ↗