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

This is a three‐arm, open‐label, randomized controlled trial conducted at a diabetesclinic in Tehran, Iran. Eligible patients ‐ adults with type 2 diabetes, moderatehypertriglyceridemia, and overweight or obesity (BMI 25‐35 kg/m²) ‐ will be enrolledthrough consecutive sampling and randomly assigned in a 1:1:1 ratio to one of three12‐week dietary interventions: a moderate low‐carbohydrate, high‐protein diet; a moderatelow‐carbohydrate, high‐fat diet; or a standard diet consistent with usual clinicalrecommendations. No placebo is used, given the nature of the intervention.The primary objective is to determine and compare changes in glycemic indices ‐ HbA1c andfasting blood glucose ‐ before and after the 12‐week intervention, both within each ofthe three groups and between groups. Secondary objectives include comparing changes inlipid profile (triglycerides, total cholesterol, LDL‐C, and HDL‐C, with triglyceridereduction considered a key outcome of interest), anthropometric indices (body weight,BMI, and waist circumference), and systolic and diastolic blood pressure across the threegroups. The study will also evaluate the level of dietary adherence in each group ‐measured through monthly self‐reported adherence questionnaires and 24‐hour dietaryrecalls ‐ and examine how adherence relates to the observed changes in glycemic, lipid,and anthropometric measures. The incidence of diet‐related side effects or adverse eventswill be compared across groups during the 12‐week intervention and during a subsequent30‐day follow‐up period.Doses of participants' existing medications for diabetes, blood lipids, and bloodpressure will be kept constant throughout the study wherever clinically safe to do so, inorder to isolate and attribute observed changes to the dietary intervention itself ratherthan to changes in medication. Participants will be contacted monthly by phone foradherence support and safety monitoring, and will have blood samples (fasting glucose,HbA1c, and full lipid profile), body weight, waist circumference, and blood pressuremeasured at baseline and again at the end of the 12‐week intervention, followed by oneadditional phone contact one month after the intervention ends to assess generalwell‐being and any delayed adverse events (without repeat laboratory or anthropometricmeasurement at that final contact).Applied objectives of the study include generating local, high‐quality randomized‐trialevidence to support individualized dietary choices (protein‐focused versus fat‐focusedlow‐carbohydrate approaches) for Iranian patients with type 2 diabetes andhypertriglyceridemia, with attention to macronutrient quality (complex/fiber‐richcarbohydrates, predominantly plant‐based protein, unsaturated fats) consistent with theIranian dietary pattern; assessing real‐world dietary adherence and identifying barriersand facilitators relevant to clinical practice; and providing preliminary evidence thatcould inform future, longer‐duration studies (6‐12 months) examining potential reductionsin medication requirements and the durability of metabolic improvements. Given the short12‐week intervention period, the trial is not designed to draw conclusions aboutlong‐term sustainability of effects.