Evaluation of the effect of curcumin and zinc co-supplementation on glycemic measurements, lipid profiles, and inflammatory and antioxidant biomarkers in overweight or obese prediabetic patients: a study protocol for a randomized double-blind placebo-controlled phase 2 clinical trial

Abstract

Background: The prevalence of prediabetes is increasing worldwide. Unfortunately, prediabetes is related to non-communicable diseases. A high risk of developing type 2 diabetes mellitus (T2DM) is reported in people with prediabetes. Curcumin, a polyphenol, might lead to its therapeutic role in obesity and some obesity-related metabolic diseases. Zinc is a trace element that plays a key role in the synthesis and action of insulin, carbohydrate metabolism, and decreasing inflammation. There has been no clinical trial of zinc and curcumin co-supplementation in patients with prediabetes. In previous studies, the single administration of zinc or curcumin has not been conducted on many of the studied markers in prediabetic patients.

Methods: The purpose of this randomized double-blind placebo-controlled clinical trial is to investigate the effect of curcumin and zinc co-supplementation on glycemic measurements, lipid profiles, and inflammatory and antioxidant biomarkers among 84 prediabetic patients with body mass index (BMI) between 25 and 35. Also, liver enzyme, serum zinc, urine zinc, blood pressure, anthropometric parameters, quality of life, adherence to co-supplementation, the side effects of co-supplementation, physical activity, and dietary intake will be assessed. Women or men (18-50 years old for men and 18 years to before menopause for women) will be followed for 3 months (90 days). This study will be conducted at Yazd Diabetes Research Clinic, Shahid Sadoughi University of Medical Sciences.

Discussion: A diet rich in antioxidants, polyphenols, and phytochemicals has been shown to have a beneficial role in prediabetes. According to the beneficial properties of curcumin or zinc and inadequate evidence, RCTs are needed to assess the effect of curcumin and zinc co-supplementation in native prediabetes patients. We hope the results of the present trial, negative or positive, fill this gap in the literature and facilitate the approach for a much larger, multi-center clinical trial. In conclusion, a synergic effect of co-supplementation along with a weight-loss diet may delay the progression to type 2 diabetes mellitus.

Trial registration: Iranian Registry of Clinical Trials (IRCT) IRCT20190902044671N1 . Registered on 11 October 2019.

Keywords: Antioxidant biomarkers; Curcumin; Glycemic measurement; Inflammatory biomarkers; Lipid profile; Prediabetes; Randomized controlled trial; Zinc.

Fig. 1

Study design flow chart. RCT, randomized controlled trial; IPAQ-SF, Short Form of International Physical Activity Questionnaire; SF-36, Short Form 36 Questionnaire

Fig. 2

Schedule of enrollment, interventions, and assessments. ABSI, A Body Shape Index; AST, aspartate aminotransferase; ALT, alanine aminotransferase; BCM, beta cell function; BMI, body mass index; DBP, diastolic blood pressure; FFM, free fat mass; FM, fat mass; FPG, fasting plasma glucose; HC, hip circumference; HbA1c, hemoglobin A1c; HDL, high-density lipoprotein cholesterol; HOMA, homeostasis model of assessment; HRQOL, health-related quality of life; hs-CRP, high-sensitivity C-reactive protein; IL-1B, interleukin-B; IPAQ-SF, Short Form of International Physical Activity Questionnaire; IR, insulin resistance; IS, insulin sensitivity; LDL, low-density lipoprotein cholesterol; MDA, malondialdehyde; MM, muscle mass; HTN, hypertension; SBP, systolic blood pressure; TAC, total blood antioxidant capacity; TTC, total cholesterol; TG, triglycerides; VLDL, very low-density lipoprotein; WC, waist circumference; WHR, waist-hip ratio; WHtR, waist-height ratio; 2hpp, 2 h post-prandial