Comparing Two Low-Carbohydrate Diets With a Standard Diet in Type 2 Diabetes

August 31, 2026 updated by: Dr Azita Hekmatdoost, National Nutrition and Food Technology Institute

Comparison of Two Moderate Low-Carbohydrate Diets (High-Protein and High-Fat) Versus a Standard Diet on Metabolic Indices in Patients With Type 2 Diabetes, Hypertriglyceridemia, and Overweight or Obesity: A Three-Arm Randomized Clinical Trial

Type 2 diabetes is often accompanied by high blood triglycerides and excess weight, and diet plays a central role in managing these conditions together. The purpose of this study is to compare the effects of two moderate low-carbohydrate diets - one higher in protein and one higher in fat - against a standard diet, on blood sugar control, blood lipids (especially triglycerides), body weight, and blood pressure in adults with type 2 diabetes, hypertriglyceridemia, and overweight or obesity.

Study Overview

Status

Not yet recruiting

Conditions

Intervention / Treatment

Detailed Description

This is a three-arm, open-label, randomized controlled trial conducted at a diabetes clinic in Tehran, Iran. Eligible patients - adults with type 2 diabetes, moderate hypertriglyceridemia, and overweight or obesity (BMI 25-35 kg/m²) - will be enrolled through consecutive sampling and randomly assigned in a 1:1:1 ratio to one of three 12-week dietary interventions: a moderate low-carbohydrate, high-protein diet; a moderate low-carbohydrate, high-fat diet; or a standard diet consistent with usual clinical recommendations. No placebo is used, given the nature of the intervention.

The primary objective is to determine and compare changes in glycemic indices - HbA1c and fasting blood glucose - before and after the 12-week intervention, both within each of the three groups and between groups. Secondary objectives include comparing changes in lipid profile (triglycerides, total cholesterol, LDL-C, and HDL-C, with triglyceride reduction considered a key outcome of interest), anthropometric indices (body weight, BMI, and waist circumference), and systolic and diastolic blood pressure across the three groups. The study will also evaluate the level of dietary adherence in each group - measured through monthly self-reported adherence questionnaires and 24-hour dietary recalls - and examine how adherence relates to the observed changes in glycemic, lipid, and anthropometric measures. The incidence of diet-related side effects or adverse events will be compared across groups during the 12-week intervention and during a subsequent 30-day follow-up period.

Doses of participants' existing medications for diabetes, blood lipids, and blood pressure will be kept constant throughout the study wherever clinically safe to do so, in order to isolate and attribute observed changes to the dietary intervention itself rather than to changes in medication. Participants will be contacted monthly by phone for adherence support and safety monitoring, and will have blood samples (fasting glucose, HbA1c, and full lipid profile), body weight, waist circumference, and blood pressure measured at baseline and again at the end of the 12-week intervention, followed by one additional phone contact one month after the intervention ends to assess general well-being and any delayed adverse events (without repeat laboratory or anthropometric measurement at that final contact).

Applied objectives of the study include generating local, high-quality randomized-trial evidence to support individualized dietary choices (protein-focused versus fat-focused low-carbohydrate approaches) for Iranian patients with type 2 diabetes and hypertriglyceridemia, with attention to macronutrient quality (complex/fiber-rich carbohydrates, predominantly plant-based protein, unsaturated fats) consistent with the Iranian dietary pattern; assessing real-world dietary adherence and identifying barriers and facilitators relevant to clinical practice; and providing preliminary evidence that could inform future, longer-duration studies (6-12 months) examining potential reductions in medication requirements and the durability of metabolic improvements. Given the short 12-week intervention period, the trial is not designed to draw conclusions about long-term sustainability of effects.

Study Type

Interventional

Enrollment (Estimated)

168

Phase

  • Not Applicable

Contacts and Locations

This section provides the contact details for those conducting the study, and information on where this study is being conducted.

Study Contact

Participation Criteria

Researchers look for people who fit a certain description, called eligibility criteria. Some examples of these criteria are a person's general health condition or prior treatments.

Eligibility Criteria

Ages Eligible for Study

  • Adult
  • Older Adult

Accepts Healthy Volunteers

No

Description

Inclusion Criteria:

Diagnosed with type 2 diabetes mellitus for ≥6 months Fasting serum triglycerides between 200-399 mg/dL (based on the average of two measurements taken within a two-week period) Body mass index (BMI) between 25 and 35 kg/m² Age between 30 and 70 years If currently taking any medication for diabetes, dyslipidemia, or hypertension, the dose must have been stable for at least 8 weeks prior to enrollment, with confirmed adherence (having hypertension is not itself an inclusion requirement; only medication dose stability is required if such medication is being taken) Able to follow the prescribed diet Willing and able to provide informed consent

Exclusion Criteria:

Fasting triglycerides ≥400 mg/dL or <200 mg/dL HbA1c >10.5% eGFR <30 mL/min/1.73m² Type 1 diabetes or rare/uncommon metabolic disorders Severe renal, cardiac, or hepatic disease, or active pancreatitis Established cardiovascular disease (myocardial infarction, stroke, coronary angioplasty or bypass surgery, or heart failure) - controlled hypertension alone does not exclude Pregnancy, breastfeeding, or planning pregnancy during the study Psychiatric disorder or social circumstances that would prevent adherence to the dietary protocol Change in dose or type of diabetes, lipid-lowering, or blood-pressure medication within the 8 weeks before enrollment or during the study Use of weight-loss medications, protein supplements, or probiotics Body weight change >3% within the past 6 months (based on medical records or physician confirmation, not self-report alone) Withdrawal of consent to continue participation

Study Plan

This section provides details of the study plan, including how the study is designed and what the study is measuring.

How is the study designed?

Design Details

  • Primary Purpose: Treatment
  • Allocation: Randomized
  • Interventional Model: Parallel Assignment
  • Masking: None (Open Label)

Arms and Interventions

Participant Group / Arm
Intervention / Treatment
Experimental: High-Protein Low-Carbohydrate Diet
Other: High-Fat Low-Carbohydrate Diet
A calorie-restricted (500 kcal/day below baseline needs) diet providing 40% of energy from complex carbohydrates, 45% from fat (35% unsaturated with a 4:1 MUFA/PUFA ratio, 10% saturated), and 15% from protein, delivered over 12 weeks as 5 individualized daily meals.
Other: Standard diet
A calorie-restricted (500 kcal/day below baseline needs) standard diet providing 55% of energy from complex carbohydrates, 30% from fat (20% unsaturated with a 4:1 MUFA/PUFA ratio, 10% saturated), and 15% from protein, delivered over 12 weeks as 5 individualized daily meals.
Experimental: High-Fat Low-Carbohydrate Diet
Other: Standard diet
A calorie-restricted (500 kcal/day below baseline needs) standard diet providing 55% of energy from complex carbohydrates, 30% from fat (20% unsaturated with a 4:1 MUFA/PUFA ratio, 10% saturated), and 15% from protein, delivered over 12 weeks as 5 individualized daily meals.
Other: High-Protein Low-Carbohydrate Diet
A calorie-restricted (500 kcal/day below baseline needs) diet providing 40% of energy from complex carbohydrates, 30% from fat (20% unsaturated with a 4:1 MUFA/PUFA ratio, 10% saturated), and 30% from protein (15% plant-based), delivered over 12 weeks as 5 individualized daily meals.
Active Comparator: Standard diet
Other: High-Fat Low-Carbohydrate Diet
A calorie-restricted (500 kcal/day below baseline needs) diet providing 40% of energy from complex carbohydrates, 45% from fat (35% unsaturated with a 4:1 MUFA/PUFA ratio, 10% saturated), and 15% from protein, delivered over 12 weeks as 5 individualized daily meals.
Other: High-Protein Low-Carbohydrate Diet
A calorie-restricted (500 kcal/day below baseline needs) diet providing 40% of energy from complex carbohydrates, 30% from fat (20% unsaturated with a 4:1 MUFA/PUFA ratio, 10% saturated), and 30% from protein (15% plant-based), delivered over 12 weeks as 5 individualized daily meals.

What is the study measuring?

Primary Outcome Measures

Outcome Measure
Time Frame
Change in fasting serum triglyceride (TG) level
Time Frame: Baseline to Week 12
Baseline to Week 12

Secondary Outcome Measures

Outcome Measure
Measure Description
Time Frame
Change in glycated hemoglobin (HbA1c)
Time Frame: Baseline to Week 12
Baseline to Week 12
Change in fasting blood glucose (FBS)
Time Frame: Baseline to Week 12
Baseline to Week 12
Change in total cholesterol
Time Frame: Baseline to Week 12
Baseline to Week 12
Change in LDL-C
Time Frame: Baseline to Week 12
Baseline to Week 12
Change in systolic blood pressure
Time Frame: Baseline to Week 12
Baseline to Week 12
Change in diastolic blood pressure
Time Frame: Baseline to Week 12
Baseline to Week 12
Change in body weight
Time Frame: Baseline to Week 12
Baseline to Week 12
Change in BMI
Time Frame: Baseline to Week 12
Baseline to Week 12
Change in waist circumference
Time Frame: Baseline to Week 12
Baseline to Week 12
Level of dietary adherence
Time Frame: Baseline to Week 12
Assessed monthly throughout the 12-week intervention
Baseline to Week 12
Incidence of diet-related adverse events
Time Frame: From baseline through the 12-week intervention and a subsequent 30-day follow-up period
From baseline through the 12-week intervention and a subsequent 30-day follow-up period

Collaborators and Investigators

This is where you will find people and organizations involved with this study.

Sponsor

National Nutrition and Food Technology Institute

Study record dates

These dates track the progress of study record and summary results submissions to ClinicalTrials.gov. Study records and reported results are reviewed by the National Library of Medicine (NLM) to make sure they meet specific quality control standards before being posted on the public website.

Study Major Dates

Study Start (Estimated)

September 20, 2026

Primary Completion (Estimated)

September 20, 2026

Study Completion (Estimated)

September 20, 2026

Study Registration Dates

First Submitted

August 31, 2026

First Submitted That Met QC Criteria

August 31, 2026

First Posted (Actual)

September 3, 2026

Study Record Updates

Last Update Posted (Actual)

September 3, 2026

Last Update Submitted That Met QC Criteria

August 31, 2026

Last Verified

August 1, 2026

More Information

Terms related to this study

Keywords

Additional Relevant MeSH Terms

Other Study ID Numbers

  • 43019892

Plan for Individual participant data (IPD)

Plan to Share Individual Participant Data (IPD)?

UNDECIDED

Drug and device information, study documents

Studies a U.S. FDA-regulated drug product

No

Studies a U.S. FDA-regulated device product

No

This information was retrieved directly from the website clinicaltrials.gov without any changes. If you have any requests to change, remove or update your study details, please contact register@clinicaltrials.gov. As soon as a change is implemented on clinicaltrials.gov, this will be updated automatically on our website as well.

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