Role of resistant starch on diabetes risk factors in people with prediabetes: Design, conduct, and baseline results of the STARCH trial

Abstract

Dietary resistant starch (RS) might alter gastrointestinal tract function in a manner that improves human health, particularly among adults at risk for diabetes. Here, we report the design and baseline results (with emphasis on race differences) from the STARCH trial, the first comprehensive metabolic phenotyping of people with prediabetes enrolled in a randomized clinical trial testing the effect of RS on risk factors for diabetes. Overweight/obese participants (BMI≥27kg/m2 and weight≤143kg), age 35-75y, with confirmed prediabetes were eligible. Participants were randomized to consume 45g/day of RS (RS=amylose) or amylopectin (Control) for 12weeks. The study was designed to evaluate the effect of RS on insulin sensitivity and secretion, ectopic fat, and inflammatory markers. Secondary outcomes included energy expenditure, substrate oxidation, appetite, food intake, colonic microbial composition, fecal and plasma levels of short-chain fatty acids, fecal RS excretion, and gut permeability. Out of 280 individuals screened, 68 were randomized, 65 started the intervention, and 63 were analyzed at baseline (mean age 55y, BMI 35.6kg/m2); 2 were excluded from baseline analyses due to abnormal insulin and diabetes. Sex and race comparisons at baseline were reported. African-Americans had higher baseline acute insulin response to glucose (AIRg measured by frequently sampled intravenous glucose tolerance test) compared to Caucasians, despite having less visceral adipose tissue mass and intrahepatic lipid; all other glycemic variables were similar between races. Sleep energy expenditure was ~90-100kcal/day lower in African-Americans after adjusting for insulin sensitivity and secretion. This manuscript provides an overview of the strategy used to enroll people with prediabetes into the STARCH trial and describes methodologies used in the assessment of risk factors for diabetes. Clinicaltrials.gov identifier: STARCH (NCT01708694). The present study reference can be found here: https://ichgcp.net/clinical-trials-registry/NCT01708694. Submission Category: "Study Design, Statistical Design, Study Protocols".

Keywords: Energy metabolism; Gut permeability; Insulin sensitivity; Microbiota; Prediabetes; Resistant starch.

Conflict of interest statement

Conflict of interest

Louisiana State University and Pennington Biomedical Research Center have an interest in the intellectual property surrounding the SmartIntake app and Remote Food Photography Method and Corby Martin is an inventor of the technology. Michael Keenan has also received research funding from Ingredion Incorporated and gifts of their products for use in his future research. None of the other authors reported a conflict of interest related to the study.

Copyright © 2017. Published by Elsevier Inc.

Figures

Fig. 1

Protocol and procedures. BMI, body mass index; DXA, dual-energy X-ray absorptiometry; FSIGTT, frequently sampled intravenous glucose tolerance test; 1H-MRS, proton magnetic resonance spectroscopy; HbA1c, hemoglobin A1c; VAS, visual analog scale.

Fig. 2

CONSORT diagram.