scholarly journals The protection of Gαz-null NOD mice from hyperglycemia is sexually dimorphic and only partially β-cell autonomous

2021 ◽  
Author(s):  
Rachel J. Fenske ◽  
Darby C. Peter ◽  
Haley N. Wienkes ◽  
Michael D. Schaid ◽  
Austin Reuter ◽  
...  
Keyword(s):  
Glucose Tolerance ◽  
Cell Function ◽  
Body Burden ◽  
Nod Mice ◽  
The Body ◽  
Negative Regulator ◽  
Oral Glucose ◽  
Sexually Dimorphic ◽  
Β Cell ◽  
G Protein Alpha Subunit

AbstractThe mechanisms that underlie the β-cell pathophysiology of Type 1 Diabetes (T1D) are not fully understood. Our group has defined the unique heterotrimeric G protein alpha-subunit, Gαz, as a key negative regulator of β-cell signal transduction pathways. Non-obese diabetic (NOD) mice lacking Gαz throughout the body are protected from developing T1D-like hyperglycemia. To determine whether this phenotype is β-cell autonomous, we generated and validated a β-cell-specific Gαz knockout (βKO) on the NOD background and characterized the phenotype of female and male cohorts. Long-term hyperglycemia incidence was lower in Gαz βKO mice as compared to wild-type (WT) controls, but, unlike global Gαz knockout mice, this protection was incomplete. While young male and female Gαz βKO NOD mice had improved glucose tolerance, WT NOD males were significantly less glucose tolerant than females, and only female Gαz βKO mice retained improved glucose tolerance at 28-29 weeks of age. Conversely, β-cell-specific Gαz loss only influenced insulitis in 28-29-week old male NOD mice, a phenotype correlating directly with body burden of glucose during oral glucose challenge. Using surrogates for β-cell function and apoptosis, the partial penetrance of euglycemia in Gαz βKO NOD was best explained by an early failure to up-regulate β-cell proliferation. We conclude β-cell Gαz is an important regulator of the sexually-dimorphic T1D-like phenotype of NOD mice. Yet, other factors must be important in imparting full protection from the disease.

scholarly journals Effects of Sucralose Ingestion versus Sucralose Taste on Metabolic Responses to an Oral Glucose Tolerance Test in Participants with Normal Weight and Obesity: A Randomized Crossover Trial

Nutrients ◽  
2019 ◽  
Vol 12 (1) ◽  
pp. 29 ◽  
Author(s):  
Alexander D. Nichol ◽  
Clara Salame ◽  
Kristina I. Rother ◽  
M. Yanina Pepino
Keyword(s):  
Glucose Tolerance ◽  
Cell Function ◽  
Normal Weight ◽  
Taste Perception ◽  
Metabolic Responses ◽  
Oral Glucose ◽  
Oral Glucose Tolerance ◽  
Β Cell ◽  
Β Cell Function ◽  
Weight Groups

Here, we tested the hypothesis that sucralose differentially affects metabolic responses to labeled oral glucose tolerance tests (OGTTs) in participants with normal weight and obesity. Participants (10 with normal weight and 11 with obesity) without diabetes underwent three dual-tracer OGTTs preceded, in a randomized order, by consuming sucralose or water, or by tasting and expectorating sucralose (e.g., sham-fed; sweetness control). Indices of β-cell function and insulin sensitivity (SI) were estimated using oral minimal models of glucose, insulin, and C-peptide kinetics. Compared with water, sucralose ingested (but not sham-fed) resulted in a 30 ± 10% increased glucose area under the curve in both weight groups. In contrast, the insulin response to sucralose ingestion differed depending on the presence of obesity: decreased within 20–40 min of the OGTT in normal-weight participants but increased within 90–120 min in participants with obesity. Sham-fed sucralose similarly decreased insulin concentrations within 60 min of the OGTT in both weight groups. Sucralose ingested (but not sham-fed) increased SI in normal-weight participants by 52 ± 20% but did not affect SI in participants with obesity. Sucralose did not affect glucose rates of appearance or β-cell function in either weight group. Our data underscore a physiological role for taste perception in postprandial glucose responses, suggesting sweeteners should be consumed in moderation.

Detection of Glycemic Abnormalities in Young Adult Patients with Beta Thalassemia Major Using Continuous Glucose Monitoring System (CGMS) and Oral Glucose Tolerance Test (OGTT)

Blood ◽  
2011 ◽  
Vol 118 (21) ◽  
pp. 2158-2158
Author(s):  
Mohamed A. Yassin ◽  
Ahmed M Elawa ◽  
Ashraf T Soliman
Keyword(s):  
Glucose Tolerance ◽  
Oral Glucose Tolerance Test ◽  
Glucose Tolerance Test ◽  
Cell Function ◽  
Serum Insulin ◽  
Tolerance Test ◽  
Oral Glucose ◽  
Oral Glucose Tolerance ◽  
Β Cell ◽  
Β Cell Function

Abstract Abstract 2158 Introduction: Both insulin deficiency and insulin resistance are reported in patients with β thalassemia major (BTM). The use of continuous blood glucose monitoring system (CGMS) among the different methods for early detection of glycaemic abnormalities has not been studied thoroughly in these patients. Aims: The aims of this study were: 1. to detect glycaemic abnormalities, if any, in young adults with BTM using fasting blood glucose (FBG), oral glucose tolerance test (OGTT), 72-h continuous glucose concentration by CGMS system, and serum insulin and C-peptide concentrations 2. To compare the results of these two methods in detecting glycaemic abnormalities in these patients and 3. To calculate homeostatic model assessment (HOMA), and the quantitative insulin sensitivity check index (QUICKI) in these patients. In order to evaluate whether glycaemic abnormalities are due to insulin deficiency and/or resistance. Materials and methods: Randomly selected young adults (n = 14) with BTM were the subjects of this study. All patients were investigated using a standard oral glucose tolerance test (OGTT) (using 75 gram of glucose) and 72-h continuous glucose concentration by CGM system (Medtronic system). Fasting serum insulin and C-peptide concentrations were measured and HOMA-B, HOMA-IR were calculated accordingly. Results: Using OGTT, 5 patients had impaired fasting glucose (IFG) (Fasting BG from 5.6 to 6.9 mmol/L). Two of them had impaired glucose tolerance IGT (BG from 7.8 and < 11.1 mmol/L) and one had BG = 16.2 mmol/L after 2-hrs (diabetic). Using CGMS in addition to the glucose data measured by glucometer (3–5 times/ day), 6 patients had IFG. The maximum (postprandial) BG recorded exceeded 11.1 mmol/L in 4 patients (28.5%) (Diabetics) and was > 7.8 but < 11.1 mmol/L in 8 patients (57%) (IGT). The mean values of HOMA and QUICKI in patients with BTM were < 2.6 (1.6± 0.8) and > 0.33 (0.36±0.03) respectively ruling out significant insulin resistance in these adolescents. There was a significant negative correlation between the β-cell function (B %) on the one hand and the fasting and the 2-h BG (r= −0.6, and − 0.48, P< 0.01 respectively) on the other hand. Serum insulin concentrations were not correlated with fasting BG or ferritin levels. The average and maximum BG levels recorded by CGMS were significantly correlated with the fasting BG (r= 0.69 and 0.6 respectively with P < 0.01) and with the BG at 2-hour after oral glucose intake (r= 0.87and 0.86 respectively with P < 0.01). Ferritin concentrations were positively correlated with the fasting BG and the 2-h BG levels in the OGTT (r= 0.69, 0.43 respectively, P < 0.001) as well as with the average and the maximum BG recorded by CGM (r =0.75, and 0.64 respectively with P < 0.01). Ferritin concentrations were negatively correlated with the β-cell function (r= −0.41, P< 0.01). Conclusion: CGMS has proved to be superior to OGTT for the diagnosis of glycaemic abnormalities in young adult patients with BTM. In our patients, defective β-cell function rather than insulin resistance appeared to be the cause for these abnormalities. The significant correlations between serum ferritin concentrations and the beta cell functions suggested the importance of adequate chelation to prevent β-cell dysfunction Disclosures: No relevant conflicts of interest to declare.

scholarly journals Evaluation of Fasting State-/Oral Glucose Tolerance Test-Derived Measures of Insulin Release for the Detection of Genetically Impaired β-Cell Function

PLoS ONE ◽  
2010 ◽  
Vol 5 (12) ◽  
pp. e14194 ◽  
Author(s):  
Silke A. Herzberg-Schäfer ◽  
Harald Staiger ◽  
Martin Heni ◽  
Caroline Ketterer ◽  
Martina Guthoff ◽  
...  
Keyword(s):  
Glucose Tolerance ◽  
Oral Glucose Tolerance Test ◽  
Glucose Tolerance Test ◽  
Cell Function ◽  
Tolerance Test ◽  
Oral Glucose ◽  
Fasting State ◽  
Oral Glucose Tolerance ◽  
Β Cell ◽  
Β Cell Function

Sitagliptin prevents the development of metabolic and hormonal disturbances, increased β-cell apoptosis and liver steatosis induced by a fructose-rich diet in normal rats

2010 ◽  
Vol 120 (2) ◽  
pp. 73-80 ◽  
Author(s):  
Bárbara Maiztegui ◽  
María I. Borelli ◽  
Viviana G. Madrid ◽  
Héctor Del Zotto ◽  
María A. Raschia ◽  
...  
Keyword(s):  
Glucose Tolerance ◽  
Cell Function ◽  
Liver Steatosis ◽  
Cell Mass ◽  
Oral Glucose ◽  
Model Assessment ◽  
Metabolic Disturbances ◽  
Β Cell ◽  
Commercial Diet ◽  
Triacylglycerol Content

The aim of the present study was to test the effect of sitagliptin and exendin-4 upon metabolic alterations, β-cell mass decrease and hepatic steatosis induced by F (fructose) in rats. Normal adult male Wistar rats received a standard commercial diet without (C) or with 10% (w/v) F in the drinking water (F) for 3 weeks; animals from each group were randomly divided into three subgroups: untreated (C and F) and simultaneously receiving either sitagliptin (CS and FS; 115.2 mg/day per rat) or exendin-4 (CE and FE; 0.35 nmol/kg of body weight, intraperitoneally). Water and food intake, oral glucose tolerance, plasma glucose, triacylglycerol (triglyceride), insulin and fructosamine concentration, HOMA-IR [HOMA (homoeostasis model assessment) for insulin resistance], HOMA-β (HOMA for β-cell function) and liver triacylglycerol content were measured. Pancreas immunomorphometric analyses were also performed. IGT (impaired glucose tolerance), plasma triacylglycerol, fructosamine and insulin levels, HOMA-IR and HOMA-β indexes, and liver triacylglycerol content were significantly higher in F rats. Islet β-cell mass was significantly lower in these rats, due to an increase in the percentage of apoptosis. The administration of exendin-4 and sitagliptin to F animals prevented the development of all the metabolic disturbances and the changes in β-cell mass and fatty liver. Thus these compounds, useful in treating Type 2 diabetes, would also prevent/delay the progression of early metabolic and tissue markers of this disease.

Estimation of β-cell function from the data of the oral glucose tolerance test

2007 ◽  
Vol 292 (6) ◽  
pp. E1575-E1580 ◽  
Author(s):  
Shinji Sakaue ◽  
Shinji Ishimaru ◽  
Daisuke Ikeda ◽  
Yoshinori Ohtsuka ◽  
Toshiro Honda ◽  
...  
Keyword(s):  
Insulin Sensitivity ◽  
Glucose Tolerance ◽  
Glucose Tolerance Test ◽  
Cell Function ◽  
Tolerance Test ◽  
Oral Glucose ◽  
Sensitivity Index ◽  
Β Cell ◽  
Β Cell Function ◽  
The Relationship

Although a hyperbolic relationship between insulin secretion and insulin sensitivity has been shown, the relationship has been often questioned. We examined the relationship using oral glucose tolerance test (OGTT)-derived indexes. A total of 374 Japanese subjects who had never been given a diagnosis of diabetes underwent a 75-g OGTT. In subjects with normal glucose tolerance (NGT), the ln [insulinogenic index (IGI)] was described by a linear function of ln ( x) ( x, insulin sensitivity index) in regression analysis when the reciprocal of the insulin resistance index in homeostasis model assessment, Matsuda's index, and oral glucose insulin sensitivity index were used as x. Because the 95% confidence interval of the slope of the regression line did not necessarily include −1, the relationships between IGI and x were not always hyperbolic, but power functions IGI × xα = a constant. We thought that IGI × xα was an appropriate β-cell function estimate adjusted by insulin sensitivity and referred to it as β-cell function index (BI). When Matsuda's index was employed as x, the BI values were decreased in subjects without NGT. Log BI had a better correlation with fasting plasma glucose (PG; FPG) and 2-h PG in non-NGT subjects than in NGT subjects. In subjects with any glucose tolerance, log BI was linearly correlated with 1-h PG and glucose spike (the difference between maximum PG and FPG). In conclusion, the relationship between insulin secretion and insulin sensitivity was not always hyperbolic. The BI is a useful tool in the estimation of β-cell function with a mathematical basis.

Impact of incretin hormones on β-cell function in subjects with normal or impaired glucose tolerance

2006 ◽  
Vol 291 (6) ◽  
pp. E1144-E1150 ◽  
Author(s):  
Elza Muscelli ◽  
Andrea Mari ◽  
Andrea Natali ◽  
Brenno D. Astiarraga ◽  
Stefania Camastra ◽  
...  
Keyword(s):  
Insulin Secretion ◽  
Glucose Tolerance ◽  
Impaired Glucose Tolerance ◽  
Cell Function ◽  
Oral Glucose ◽  
Incretin Effect ◽  
Β Cell ◽  
Β Cell Function ◽  
Glucose Sensitivity ◽  
Cell Glucose

The mechanisms by which the enteroinsular axis influences β-cell function have not been investigated in detail. We performed oral and isoglycemic intravenous (IV) glucose administration in subjects with normal (NGT; n = 11) or impaired glucose tolerance (IGT; n = 10), using C-peptide deconvolution to calculate insulin secretion rates and mathematical modeling to quantitate β-cell function. The incretin effect was taken to be the ratio of oral to IV responses. In NGT, incretin-mediated insulin release [oral glucose tolerance test (OGTT)/IV ratio = 1.59 ± 0.18, P = 0.004] amounted to 18 ± 2 nmol/m2 (32 ± 4% of oral response), and its time course matched that of total insulin secretion. The β-cell glucose sensitivity (OGTT/IV ratio = 1.52 ± 0.26, P = 0.02), rate sensitivity (response to glucose rate of change, OGTT/IV ratio = 2.22 ± 0.37, P = 0.06), and glucose-independent potentiation were markedly higher with oral than IV glucose. In IGT, β-cell glucose sensitivity (75 ± 14 vs. 156 ± 28 pmol·min−1·m−2·mM−1 of NGT, P = 0.01) and potentiation were impaired on the OGTT. The incretin effect was not significantly different from NGT in terms of plasma glucagon-like peptide 1 and glucose-dependent insulinotropic polypeptide responses, total insulin secretion, and enhancement of β-cell glucose sensitivity (OGTT/IV ratio = 1.73 ± 0.24, P = NS vs. NGT). However, the time courses of incretin-mediated insulin secretion and potentiation were altered, with a predominance of glucose-induced vs. incretin-mediated stimulation. We conclude that, under physiological circumstances, incretin-mediated stimulation of insulin secretion results from an enhancement of all dynamic aspects of β-cell function, particularly β-cell glucose sensitivity. In IGT, β-cell function is inherently impaired, whereas the incretin effect is only partially affected.

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