Here is the design of a clinical trial:

Official Title: Low-Carbohydrate Dietary Pattern on Glycemic Outcomes Trial

Included conditions:
- Diabetes
- PreDiabetes
- Metabolic Disease
- Hyperglycemia
- Diet Modification
- Glucose Intolerance
- Glucose Metabolism Disorders (Including Diabetes Mellitus)
- Endocrine System Diseases

Study Armgroups:
- {'label': 'Low-Carbohydrate Diet', 'type': 'EXPERIMENTAL', 'description': 'Behavioral modification to reduce carbohydrate consumption. Target \\<40 g net carbohydrates per day for first 3 months; \\<60 g net carbohydrates per day for months 4 onwards. The intervention will consist of 4 weekly individual counseling sessions, followed by 4 group sessions held every other week, with phone follow-ups in between group sessions. For the last 3 months of the study, there will be 3 monthly group sessions and 3 telephone follow-ups.\n\nAt baseline, participants will receive written information with standard physical activity recommendations.', 'interventionNames': ['Behavioral: Low-Carbohydrate Diet']}
- {'label': 'Usual Diet', 'type': 'NO_INTERVENTION', 'description': 'No dietary intervention.\n\nAt baseline, participants will receive written information with standard dietary advice and standard physical activity recommendations.'}

Interventions:
- {'type': 'BEHAVIORAL', 'name': 'Low-Carbohydrate Diet', 'description': 'Behavioral modification to reduce carbohydrate consumption. Target \\<40 g net carbohydrates per day for first 3 months; \\<60 g net carbohydrates per day for months 4 onwards. The intervention will consist of 4 weekly individual counseling sessions, followed by 4 group sessions held every other week, with phone follow-ups in between group sessions. For the last 3 months of the study, there will be 3 monthly group sessions and 3 telephone follow-ups.\n\nAt baseline, participants will receive written information with standard physical activity recommendations.', 'armGroupLabels': ['Low-Carbohydrate Diet']}

Primary Outcomes:
- {'measure': 'Change in Hemoglobin A1c', 'description': '6-month change in Hemoglobin A1c comparing low-carbohydrate arm with usual diet arm', 'timeFrame': 'Baseline and six months'}

Please estimate the sample size based on the assumption: 
Standard deviation of change in HbA1c of 0.35%, 95% follow-up rate, 80% power, two-sided alpha of 0.05.
Sample size {14}
        The primary outcome will be the difference in the change of HbA1c between the intervention and usual diet groups. Pilot data from our group suggests that the standard deviation (SD) of 6-month change in HbA1c is 0.35%, with 6-month follow-up >â95% (follow-up rate to-date is 96%). Based on an estimated standard deviation of change in HbA1c of 0.35% and 95% follow-up, we would need a total of 150 participants (142 participants with follow-up data) to have 80% power to detect a difference in the change in HbA1c from baseline to 6âmonths of 0.17% between the intervention and usual diet groups (unpaired t tests, two-sided alpha of 0.05).