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Cardiorespiratory fitness is positively associated with increased pancreatic beta cell function independent of fatness in individuals with the metabolic syndrome: Fitness versus fatness.
Ramos, JS, Dalleck, LC, Borrani, F, Fassett, RG, Coombes, JS
Journal of science and medicine in sport. 2017;(1):45-49
Abstract
OBJECTIVES The vulnerability of individuals with the metabolic syndrome (MetS) to cardiovascular events (CVEs) is attenuated by increased cardiorespiratory fitness (CRF), despite the presence of obesity as a usual component of MetS. To better understand the importance of CRF and body fat in treating this condition, we investigated the relationship between fitness and fatness with pancreatic beta cell function (BCF) indices that are known independent predictors of CVEs. DESIGN Cross sectional study. METHODS This study included 84 individuals with MetS. BCF indices were derived from a fasted steady state (basal disposition index [DI], proinsulin, proinsulin:insulin, and proinsulin:C-peptide) and dynamic conditions via an oral glucose tolerance test (1st and 2nd phase DI). CRF and body fat percentage (BF%) were assessed via indirect calorimetry (during a maximal exercise test) and dual energy X-ray absorptiometry, respectively. RESULTS CRF was positively associated with basal DI (r=0.40, p<0.001), 1st phase DI (r=0.49, p<0.005), and 2nd phase DI (r=0.38, p=0.02). Hierarchical multiple regression analysis showed CRF was associated with basal DI (β=0.18, p=0.04), 1st phase DI (β=0.36, p=0.04), and 2nd phase DI (β=0.33, p=0.03), independent of BF% and other confounding factors including age, sex, diabetic status, anthropometric measures, lipid profile, and insulin sensitivity. No significant associations were found between CRF and proinsulin measures. BF% was not significantly correlated with BCF indices. CONCLUSIONS Increased CRF was independently associated with enhanced BCF. This study provides evidence that equal, if not more attention should be dedicated to CRF improvement relative to fat-loss for favorable pancreatic BCF and thus possible reduction in CV risk in individuals with MetS.
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Favourable metabolic effects of a eucaloric lower-carbohydrate diet in women with PCOS.
Gower, BA, Chandler-Laney, PC, Ovalle, F, Goree, LL, Azziz, R, Desmond, RA, Granger, WM, Goss, AM, Bates, GW
Clinical endocrinology. 2013;(4):550-7
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Abstract
OBJECTIVE Diet-induced reduction in circulating insulin may be an attractive nonpharmacological treatment for women with polycystic ovary syndrome (PCOS) among whom elevated insulin may exacerbate symptoms by stimulating testosterone synthesis. This study was designed to determine whether a modest reduction in dietary carbohydrate (CHO) content affects β-cell responsiveness, serum testosterone concentration and insulin sensitivity in women with PCOS. DESIGN In a crossover design, two diets ('Standard,' STD, 55:18:27% energy from carbohydrate/protein/fat; lower-carbohydrate, 41:19:40) were provided for 8 weeks in random order with a 4-week washout between. PATIENTS Thirty women with PCOS. MEASUREMENTS β-cell responsiveness assessed as the C-peptide response to glucose during a liquid meal test; insulin sensitivity from insulin and glucose values throughout the test; insulin resistance (HOMA-IR); and total testosterone by immunoassay. RESULTS Paired t-test indicated that the lower-CHO diet induced significant decreases in basal β-cell response (PhiB), fasting insulin, fasting glucose, HOMA-IR, total testosterone and all cholesterol measures, and significant increases in insulin sensitivity and dynamic ('first-phase') β-cell response. The STD diet induced a decrease in HDL-C and an increase in the total cholesterol-to-HDL-C ratio. Across all data combined, the change in testosterone was positively associated with the changes in fasting insulin, PhiB and insulin AUC (P < 0·05). CONCLUSIONS In women with PCOS, modest reduction in dietary CHO in the context of a weight-maintaining diet has numerous beneficial effects on the metabolic profile that may lead to a decrease in circulating testosterone.
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Visceral fat resection in humans: effect on insulin sensitivity, beta-cell function, adipokines, and inflammatory markers.
Lima, MM, Pareja, JC, Alegre, SM, Geloneze, SR, Kahn, SE, Astiarraga, BD, Chaim, ÉA, Baracat, J, Geloneze, B
Obesity (Silver Spring, Md.). 2013;(3):E182-9
Abstract
OBJECTIVE The visceral fat is linked to insulin resistance, the metabolic syndrome, type 2 diabetes and an increased cardiovascular risk, but it is not clear whether it has a causative role. DESIGN AND METHODS Surgical resection of this fat depot is a research model to address this issue. Twenty premenopausal women with metabolic syndrome and grade III obesity were randomized to undergo Roux-en-Y gastric bypass (RYGBP) either alone or combined with omentectomy. Insulin sensitivity (IS; euglycemic-hyperinsulinemic clamp), acute insulin response to glucose (AIR; intravenous glucose tolerance test), disposition index (DI = AIR × IS measured by clamp), lipid profile, adipokine profile (leptin, adiponectin, resistin, visfatin, interleukin-6, TNF-α, MCP-1), ultra-sensitive C-reactive protein (CRP), body composition, and abdominal fat echography were assessed prior to surgery and 1, 6, and 12 months post-surgery. RESULTS Omentectomy was associated with greater weight loss at all time points. IS improved similarly in both groups. Omentectomy was associated to lower CRP after 12 months, but it did not influence adipokines and other metabolic parameters. Among non-diabetic subjects, omentectomy was associated with a preservation of baseline AIR after 12 months (as opposed to deterioration in the control group) and a greater DI after 6 and 12 months. CONCLUSION Although omentectomy did not enhance the effect of RYGBP on insulin sensitivity and adipokines, it was associated with a preservation of insulin secretion, a greater weight loss, and lower CRP.