Insulin-Sensitizing Effects on Muscle and Adipose Tissue after Dietary Fiber Intake in Men and Women with Metabolic Syndrome
- M. Denise Robertson
- John W. Wright
- Emmanuelle Loizon
- Cyrille Debard
- Hubert Vidal
- Fariba Shojaee-Moradie
- David Russell-Jones
- A. Margot Umpleby
Context:
Dietary fibers have been associated with a reduced incidence of type 2 diabetes mellitus in epidemiological studies; however, the precise mechanisms are unknown.
Objective:
The objective of the study was to evaluate the efficacy and site of action of an insoluble dietary fiber derived from maize (HAM-RS2) in improving insulin resistance in subjects at increased risk of type 2 diabetes mellitus.
Design:
This study was a randomized, controlled crossover, dietary intervention study.
Setting:
The study was conducted at the Centre for Diabetes, Endocrinology, and Research, Royal Surrey County Hospital, Guildford, United Kingdom.
Participants:
Fifteen men and women with insulin resistance participated in the study.
Intervention:
The intervention included 40 g/d HAM-RS2 compared with a matched placebo for 8 wk.
Main Outcome Measures:
After each supplement, participants underwent a two-step hyperinsulinemic-euglycemic clamp study with the addition of glucose tracers; a meal tolerance test; arteriovenous sampling across forearm muscle tissue; and a sc adipose tissue biopsy for assessment of gene expression.
Results:
There was enhanced uptake of glucose into the forearm muscle measured by arteriovenous sampling (65 ± 15% increase after resistant starch; P < 0.001). Adipose tissue function was also affected, with enhanced fatty acid suppression after HAM-RS2 treatment and an increase in gene expression for hormone sensitive lipase (P = 0.005), perilipin (P = 0.011), lipoprotein lipase (P = 0.014), and adipose triglyceride lipase (P = 0.03) in biopsy samples. There was no effect on the insulin sensitivity of hepatic glucose production or plasma lipids after HAM-RS2.
Conclusion:
HAM-RS2 improved peripheral but not hepatic insulin resistance and requires further study as an intervention in patients with or at risk for type 2 diabetes.
