Mannose is an insulin-regulated metabolite reflecting whole-body insulin sensitivity in man.

Mannose is a glucose-associated serum metabolite mainly released by the liver. Recent studies have shown several unexpected pleiotropic effects of mannose including increased regulatory T cells (Tregs), prevention of auto-immune disease and ability to reduce growth of human cancer cells. We have previously shown in large cohorts that elevated serum mannose levels are associated with future development of type 2 diabetes (T2D) and cardiovascular disease. However, potential direct effects of mannose on insulin sensitivity in vivo or in vitro are unknown. We here show that administration of mannose (0.1 g/kg BW twice daily) for one week in man did not elicit negative effects on meal-modified glucose tolerance, markers of inflammation or insulin levels. Tregs number and insulin signaling in human liver cells were unchanged. These data suggest that mannose is a marker, and not a mediator, of insulin resistance. To verify this, we examined serum mannose levels during long-term euglycemic hyperinsulinemic clamps in non-diabetic and T2D individuals. Mannose was reduced by insulin infusion in proportion to whole-body insulin sensitivity. Thus, mannose is a biomarker of insulin resistance which may be useful for the early identification of diabetic individuals with insulin resistance and increased risk of its complications.

A novel cobiotic-based preventive approach against high-fat diet-induced adiposity, nonalcoholic fatty liver and gut derangement in mice.

BACKGROUND: High-fat diets (HFDs) induce systemic inflammation, gut microbial derangements and disturb metabolic homeostasis, resulting in weight gain, insulin resistance and nonalcoholic fatty liver (NAFL). Numerous antioxidants and prebiotic/probiotics per se may prevent HFD-associated comorbidities, but there are no reports related to their combination. OBJECTIVE: In the present study, we aim to evaluate a cobiotic combination of lycopene (antioxidant) and isomalto-oligosaccharides (IMOs, a prebiotic) for prevention of HFD-induced alterations. DESIGN: Male Swiss albino mice were fed either normal pellet diet (NPD) or HFD and lycopene (5 and 10 mg kg(-1)), IMOs (0.5 and 1 g kg(-1)) or their combination for 12 weeks. Systemic adiposity, glucose tolerance, insulin sensitivity, feeding regulators in hypothalamus, hepatosteatosis and liver inflammation, cecal short chain fatty acids (SCFAs), serum inflammatory cytokines, gut morphology and alterations in selected gut microbes were studied. RESULTS: Lycopene, IMOs and their combination prevented weight gain, adiposity, improved adipose tissue fat mobilization and reduced insulin resistance. Hypothalamic orexigenic and anorectic genes have also been modulated by these treatments. Dietary interventions prevented NAFL-like symptoms and improved glucose homeostasis. Improvement in selected gut microbial abundance and SCFA concentration along with reduced systemic inflammation, metabolic endotoxemia and improved ileal and colonic health were observed in mice supplemented with lycopene, IMOs and their combination. Interestingly, cobiotic combination synergistically improved many of the HFD-induced alterations. CONCLUSION: The present work provide evidence that new approach based on cobiotic combination (antioxidant plus prebiotic) can be employed to develop novel class of functional foods for their application against HFD-associated pathological complications.