1.
Grape pomace polyphenols improve insulin response to a standard meal in healthy individuals: A pilot study.
Costabile, G, Vitale, M, Luongo, D, Naviglio, D, Vetrani, C, Ciciola, P, Tura, A, Castello, F, Mena, P, Del Rio, D, et al
Clinical nutrition (Edinburgh, Scotland). 2019;(6):2727-2734
Abstract
BACKGROUND & AIMS Dietary polyphenols have beneficial effects on glucose/lipid metabolism in subjects at high risk to develop type 2 diabetes; however, the underlying mechanisms are not clear. We aimed to evaluate: 1) the acute effects of the consumption of a drink rich in polyphenols from red grape pomace (RGPD) on glucose/insulin and triglyceride responses to a standard meal in healthy individuals, and, 2) the relationship between plasma levels of phenolic metabolites and metabolic parameters. METHODS Twelve healthy men, aged 20-40 years participated in a randomized, controlled study according to a cross-over design. After a 3-day low-polyphenol diet, all participants consumed, on two different days and separated by a one week interval, after an overnight fast, a drink rich in polyphenols (1.562 g gallic acid equivalents (GAE)) or a control drink (CD, no polyphenols), followed after 3 h by a standard meal (960 kcal, 18% protein, 30% fat, 52% CHO). Blood samples were taken at fasting, 3 h after the drink, over 5 h after the standard meal and at fasting on the next day to measure plasma concentrations of glucose, insulin, triglyceride and phenolic metabolites. RESULTS Glycemic and triglyceride post-meal responses were similar after both the RGPD and the control drink. In contrast, postprandial insulin incremental area (iAUC0-5h) was 31% lower (p < 0.05), insulin secretion index was 18% lower (p < 0.016) and insulin sensitivity (SI) index was 36% higher (p = 0.037) after the RGPD compared to CD. Among phenolic metabolites, gallic acid correlated inversely with the insulin response (r = -0.604; p = 0.032) and positively with the SI index (r = 0.588, p = 0.037). CONCLUSIONS RGPD consumption acutely reduced postprandial insulin levels and improved insulin sensitivity. This effect could be likely related to the increase in gallic acid levels. This drink, added to usual diet, could contribute to increase the daily intake of polyphenols, with potential health benefits. CLINICALTRIALS. GOV IDENTIFIER NCT02865278.
2.
Comparative evaluation of simple indices of insulin resistance.
Vaccaro, O, Masulli, M, Cuomo, V, Rivellese, AA, Uusitupa, M, Vessby, B, Hermansen, K, Tapsell, L, Riccardi, G
Metabolism: clinical and experimental. 2004;(12):1522-6
Abstract
Various surrogate methods for the quantification of insulin sensitivity have been proposed. A comparative evaluation is lacking and is relevant for the standardization of investigative methods and comparability of results. The aims of the study were to perform a comparative validation of fasting insulin, homeostasis model assessment (HOMA), Quantitative Insulin Sensitivity Check Index (QUICKI), and revised-QUICKI (R-QUICKI) against minimal model derived estimates of insulin sensitivity (SI(MM)) in nondiabetic people and to carry out a comparative evaluation of the ability of these indices as means for the identification of individuals with the metabolic syndrome (MS) on a population basis. We used 2 data sets defined as "validation sample" and "prevalence sample". Validation sample: a total of 162 healthy men and women aged 30 to 65 years were studied by frequently sampled intravenous glucose tolerance test (FSIVGTT). SI(MM) was calculated with the Minmod program. Prevalence sample: a total of 2,731 nondiabetic men and women aged 35 to 65 years were studied. In both samples, anthropometry, blood pressure, fasting glucose, insulin, triglycerides, high-density lipoprotein (HDL) cholesterol, and free fatty acid (FFA) were measured. HOMA, QUICKI, and R-QUICKI were calculated. The MS was defined according to the Adult Treatment Panel III. Validation sample: insulin, HOMA, QUICKI, and R-QUICKI significantly correlated with SI(MM) (r = -0,53, -0.52, 0.41, 0.33; all P < .001). The finding was confirmed in obese (body mass index [BMI] > or =25 kg/m(2)), but in the normal weight, the correlation coefficient for QUICKI was significantly smaller than for the other indices. Receiver operator characteristic (ROC) curve analysis performed with SI(MM) below or above the lowest 25th percentile (ie, insulin resistance yes, no) as the outcome variable and each of the 4 indices as the test variable showed no significant differences in the areas under the curve. Prevalence sample: prevalence of the MS progressively increased across quartiles of insulin resistance as evaluated by any of the 4 indices, with no significant differences between them. The novel indices QUICKI and R-QUICKI do not perform better than HOMA and fasting insulin as surrogate measures of insulin resistance or means for the identification of people with MS in the general population.
3.
Insulin resistance is independently associated with postprandial alterations of triglyceride-rich lipoproteins in type 2 diabetes mellitus.
Annuzzi, G, De Natale, C, Iovine, C, Patti, L, Di Marino, L, Coppola, S, Del Prato, S, Riccardi, G, Rivellese, AA
Arteriosclerosis, thrombosis, and vascular biology. 2004;(12):2397-402
Abstract
OBJECTIVE To evaluate the role of insulin resistance in development of postprandial dyslipidemia in type 2 diabetic patients in an experimental setting in which these patients were compared with nondiabetic subjects at similar glucose and insulin blood levels. METHODS AND RESULTS Eight type 2 diabetic patients in optimal blood glucose control and 7 control subjects (aged 50.0+/-2.6 and 48.1+/-1.3 years; body mass index 28.3+/-1.2 and 25.6+/-1.1 kg/m2; fasting plasma triglycerides 1.12+/-0.13 and 0.87+/-0.08 mmol/L, respectively; mean+/-SEM; NS) consumed a mixed meal during an 8-hour hyperinsulinemic glycemic clamp. Mean blood glucose during clamp was approximately 7.8 mmol/L, and plasma insulin during the preprandial steady state was approximately 480 pmol/L in both groups, that differed for insulin sensitivity (M/I value lower in diabetic subjects [1.65+/-0.30 and 3.42+/-0.60; P<0.05]). Subjects with diabetes had higher postprandial levels of lipids and apolipoprotein B (apoB) in large very low-density lipoprotein (incremental area for triglycerides 1814+/-421 versus 549+/-153 micromol/Lx6 hours; P<0.05; cholesterol 694+/-167 versus 226+/-41 micromol/Lx6 hours; P<0.05; apoB-48 6.3+/-1.0 versus 2.6+/-0.7 mg/Lx6 hours; P<0.05; apoB-100 56.5+/-14.9 versus 26.2+/-11.0 mg/Lx6 hours; NS). Basal lipoprotein lipase (LPL) activity before and after meal was higher in diabetic subjects, whereas postheparin LPL activity 6 hours after the meal was similar. CONCLUSIONS Insulin resistance is also associated with postprandial lipoprotein abnormalities in type 2 diabetes after acute correction for hyperglycemia and hyperinsulinemia.