Effect of Different Carbohydrate Intake Patterns on Glycemic Control in Patients With Type 1 Diabetes

Yang Tao80 enrolled

Overview

This multicenter, randomized, controlled, open-label clinical trial aims to evaluate the effects of different carbohydrate intake patterns on glycemic control in adults with type 1 diabetes. Participants will first complete a 2-week run-in period and will then be randomly assigned in a 1:1 ratio to one of two dietary groups. Both diets provide similar proportions of total energy from carbohydrates, protein, and fat, but differ in the sources of staple carbohydrates. In the moderate carbohydrate diet group, most staple foods are refined grains, whereas in the diverse carbohydrate diet group, approximately half of the staple foods are whole grains and legumes. 80 participants will follow the assigned dietary intervention for 2 weeks, followed by a 12-week follow-up period. The primary outcome is time in range (TIR), defined as the percentage of time that glucose levels are within the target range, measured using continuous glucose monitoring. Other measures of glycemic control, glycemic variability, insulin requirements, body measurements, metabolic indicators, and safety will also be evaluated. Exploratory analyses will assess potential changes in gut microbiota, immune function, and metabolomic profiles.

Medical nutrition therapy is an important component of the management of type 1 diabetes. In addition to the amount of carbohydrate consumed, the source and quality of dietary carbohydrates may influence glycemic responses and glycemic variability. However, evidence regarding the effects of different carbohydrate intake patterns in people with type 1 diabetes remains limited, particularly when glycemic outcomes are assessed using continuous glucose monitoring. This study is designed to compare two dietary patterns that provide comparable total energy intake and the same target macronutrient distribution but differ in the sources of staple carbohydrates. Individual energy intake is determined according to each participant's estimated energy requirement. In both groups, carbohydrates provide 45%-55% of total energy, protein provides 15%-20%, and fat provides 25%-35%. In the moderate carbohydrate diet (MCD) group, 90%-95% of staple foods are derived from refined grains. In the diverse carbohydrate diet (DCD) group, 45%-50% of staple foods are derived from refined grains and 45%-50% from whole grains and legumes. Thus, the principal difference between the two dietary patterns is the source and diversity of staple carbohydrates rather than total energy intake or overall macronutrient composition. By minimizing differences in total energy intake and macronutrient distribution between the two groups, this study aims to evaluate whether changing the sources and diversity of dietary carbohydrates influences glycemic control and glycemic variability in people with type 1 diabetes. In addition to clinical and metabolic assessments, exploratory analyses will evaluate changes in gut microbiota, immune function, and metabolomics to investigate potential mechanisms through which different carbohydrate intake patterns may affect glycemic control.

Interventions

diverse carbohydrate dietOTHER

Carbohydrate, protein, and fat provide 45-55%, 15-20%, and 25-35% of total dietary energy, respectively. Of the staple carbohydrate sources, 45-50% are derived from refined grains and 45-50% from whole grains and legumes. Total daily energy intake is divided among three meals, with breakfast providing 25-30% of total energy, lunch 30-40%, and dinner 30-35%.

moderate carbohydrate dietOTHER

Carbohydrate, protein, and fat provide 45-55%, 15-20%, and 25-35% of total dietary energy, respectively. Of the staple carbohydrate sources, 90-95% are derived from refined grains. Total daily energy intake is divided among three meals, with breakfast providing 25-30% of total energy, lunch 30-40%, and dinner 30-35%.

Eligibility

Sex: ALLMin age: 18 YearsMax age: 70 Years

Medical Language ↔ Plain English

Inclusion Criteria: 1. Participants who agree to participate in the study and provide written informed consent; 2. Diagnosed with type 1 diabetes mellitus according to the ADA 2024 criteria; 3. Aged 18 to 70 years, inclusive; 4. Receiving exogenous insulin therapy with a stable treatment regimen for at least 2 months before enrollment (the type of insulin should remain unchanged, while the dose may be adjusted according to blood glucose levels); 5. Body mass index (BMI) between 18.0 and 25.0 kg/m², inclusive; 6. Glycated hemoglobin A1c (HbA1c) \<11%. Exclusion Criteria: 1. Type 1 diabetes mellitus in the honeymoon phase; 2. Pregnant or breastfeeding women, or women for whom pregnancy cannot be ruled out; 3. Patients who are vegetarians or are undergoing weight loss; 4. Patients who are users of oral hypoglycemic drugs (alpha-glucosidase inhibitors, DPP-4 inhibitors, etc.); 5. Use of glucocorticoids within 30 days before enrollment; 6. History of severe food allergy; 7. Patients with acute complications such as diabetic ketoacidosis (DKA) or hyperosmolar hyperglycemic state (HHS) within the previous 6 months; 8. Patients with gastroparesis, inflammatory bowel disease or other complications; 9. Patients with macroalbuminuria (albumin-to-creatinine ratio \> 34 mg/mmol) or renal insufficiency (creatinine \> 200 μmol/L); 10. Patients with uncontrolled hyperthyroidism or hypothyroidism (Uncontrolled hyperthyroidism is defined as abnormal TSH and FT4. Uncontrolled hypothyroidism is defined as TSH \> 10 mIU/L.); 11. History of heart disease, coronary artery disease or arrhythmia; 12. Alanine aminotransferase (ALT) or aspartate aminotransferase (AST) \>3 times the upper limit of normal; 13. History of malignant tumors; history of tumors or surgery affecting digestion or nutrient absorption. Eligibility of participants with a history of benign tumors will be determined by the investigator; 14. Patients with other uncontrolled immune system diseases or uncontrolled infections; 15. Alcohol abuse, drug abuse, mental disorders, or other conditions unsuitable for study participation; 16. Any disease or condition that, in the investigator's judgment, may interfere with study participation or evaluation.

Outcomes

Primary Outcomes

Time in range (TIR)

TIR is defined as the percentage of time that glucose levels are between 3.9 and 10.0 mmol/L, as measured by continuous glucose monitoring (CGM). TIR at the end of the 2-week dietary intervention will be compared between the two groups.

Time frame: 4 weeks (2 weeks after randomization)

Secondary Outcomes

Time above range(TAR)

TAR is defined as the percentage of time that glucose levels are above 10.0 mmol/L, as measured using continuous glucose monitoring (CGM). TAR at the end of the 2-week dietary intervention will be compared between the two groups.

Time frame: 4 weeks (2 weeks after randomization)

Time below range(TBR)

TBR is defined as the percentage of time that glucose levels are below 3.9 mmol/L, as measured using continuous glucose monitoring (CGM). TBR at the end of the 2-week dietary intervention will be compared between the two groups.

Time frame: 4 weeks (2 weeks after randomization)

Mean glucose (MG)

Mean glucose is defined as the arithmetic mean of all valid glucose values recorded during the 2-week continuous glucose monitoring (CGM) period. Mean glucose at the end of the 2-week dietary intervention will be compared between the two groups.

Time frame: 4 weeks (2 weeks after randomization)

Standard deviation of glucose (SD)

SD is a continuous glucose monitoring (CGM)-derived measure of glycemic variability. SD at the end of the 2-week dietary intervention will be compared between the two groups.

Time frame: 4 weeks (2 weeks after randomization)

Glucose coefficient of variation (CV)

CV is a continuous glucose monitoring (CGM)-derived measure of glycemic variability. CV at the end of the 2-week dietary intervention will be compared between the two groups.

Time frame: 4 weeks (2 weeks after randomization)

Mean amplitude of glycemic excursions (MAGE)

MAGE is a continuous glucose monitoring (CGM)-derived measure of glycemic variability. MAGE at the end of the 2-week dietary intervention will be compared between the two groups.

Time frame: 4 weeks (2 weeks after randomization)

Largest amplitude of glycemic excursions (LAGE)

LAGE is a continuous glucose monitoring (CGM)-derived measure of glycemic variability. LAGE at the end of the 2-week dietary intervention will be compared between the two groups.

Time frame: 4 weeks (2 weeks after randomization)

Glycated albumin (GA)

Glycated albumin will be measured at the end of the 2-week dietary intervention and compared between the two groups.

Time frame: 4 weeks (2 weeks after randomization)

Glycated hemoglobin A1c (HbA1c)

HbA1c will be measured at the end of the follow-up period and compared between the two groups.

Time frame: 16 weeks (14 weeks after randomization)

C-peptide area under the curve (AUC C-peptide)

C-peptide area under the curve will be assessed during a 3-hour mixed-meal tolerance test and calculated using the trapezoidal rule. The assessment will be performed in participants with fasting C-peptide \>80 pmol/L.

Time frame: 16 weeks (14 weeks after randomization)

Glucagon area under the curve (AUC glucagon)

Glucagon area under the curve will be assessed during a 3-hour mixed-meal tolerance test and calculated using the trapezoidal rule. The assessment will be performed in participants with fasting C-peptide \>80 pmol/L.

Time frame: 16 weeks (14 weeks after randomization)

Fasting blood glucose (FBG)

Fasting blood glucose will be measured at the end of the dietary intervention and at the end of the follow-up period and compared between the two groups.