scholarly journals Meal feeding improves oral glucose tolerance in male rats and causes adaptations in postprandial islet hormone secretion that are independent of plasma incretins or glycemia

2014 ◽  
Vol 307 (9) ◽  
pp. E784-E792 ◽  
Author(s):  
Torsten P. ◽  
Benedikt A. Aulinger ◽  
Eric P. Smith ◽  
Deborah L. Drazen ◽  
Yve Ulrich-Lai ◽  
...  
Keyword(s):  
Insulin Secretion ◽  
Glucose Tolerance ◽  
Cell Function ◽  
Hormone Secretion ◽  
Insulin Response ◽  
Male Rats ◽  
Oral Glucose ◽  
Light Cycle ◽  
Oral Glucose Tolerance ◽  
Islet Hormone

Meal-fed (MF) rats with access to food for only 4 consecutive hours during the light cycle learn to eat large meals to maintain energy balance. MF animals develop behavioral and endocrine changes that permit glucose tolerance despite increased meal size. We hypothesized that enhanced activity of the enteroinsular axis mediates glucose homeostasis during MF. Cohorts of rats were allocated to MF or ad libitum (AL) regimens for 2–4 wk. Insulin secretion and glucose tolerance were determined after oral carbohydrate and intraperitoneal (ip) and intravenous (iv) glucose. MF rats ate less than AL in the first week but maintained a comparable weight trajectory thereafter. MF rats had decreased glucose excursions after a liquid mixed meal (AUC: MF 75 ± 7, AL 461 ± 28 mmol·l−1·min, P < 0.001), with left-shifted insulin secretion (AUC0–15: MF 31.0 ± 4.9, AL 9.6 ± 4.4 pM·min, P < 0.02), which peaked before a significant rise in blood glucose. Both groups had comparable fasting glucagon levels, but postprandial responses were lower with MF. However, neither intestinal expression of proGIP and proglucagon mRNA nor plasma incretin levels differed between MF and AL groups. There were no differences in the insulin response to ip or iv glucose between MF and AL rats. These findings demonstrate that MF improves oral glucose tolerance and is associated with significant changes in postprandial islet hormone secretion. Because MF enhanced β-cell function during oral but not parenteral carbohydrate administration, and was not accounted for by changes in circulating incretins, these results support a neural mechanism of adaptive insulin secretion.

scholarly journals The Leu7Pro Polymorphism of PreproNPY Is Associated with Decreased Insulin Secretion, Delayed Ghrelin Suppression, and Increased Cardiovascular Responsiveness to Norepinephrine during Oral Glucose Tolerance Test

2005 ◽  
Vol 90 (6) ◽  
pp. 3646-3652 ◽  
Author(s):  
Ulriikka Jaakkola ◽  
Tom Kuusela ◽  
Tuomas Jartti ◽  
Ullamari Pesonen ◽  
Markku Koulu ◽  
...  
Keyword(s):  
Insulin Secretion ◽  
Glucose Tolerance ◽  
Oral Glucose Tolerance Test ◽  
Baroreflex Sensitivity ◽  
Glucose Tolerance Test ◽  
Hormone Secretion ◽  
Tolerance Test ◽  
Oral Glucose ◽  
Oral Glucose Tolerance ◽  
Glucose Ingestion

Context: Neuropeptide Y (NPY) plays a role in angiogenesis, cardiovascular regulation, and hormone secretion. The leucine7 to proline7 (Leu7Pro) polymorphism of preproNPY is associated with vascular diseases and has an impact on hormone levels in healthy subjects. Objective: The current study investigated the role of the Leu7Pro polymorphism in metabolic and cardiovascular autonomic regulation. Design and Subjects: A 5-h oral glucose tolerance test was performed on 27 healthy volunteers representing two preproNPY genotypes (Leu7/Pro7 and Leu7/Leu7) matched for age, sex, body mass index and physical activity. Main Outcome Measures: Simultaneously we performed cardiovascular autonomic function tests and plasma measurements of sympathetic transmitters, glucose, insulin, and ghrelin. Results: The subjects with Leu7/Pro7 genotype had decreased plasma NPY, norepinephrine (NE), and insulin concentrations and insulin to glucose ratios. The suppression of ghrelin concentrations after glucose ingestion was delayed in these subjects. They also had increased heart rate variability indices and baroreflex sensitivity. However, they displayed significant negative association of NE concentration with variability of low-frequency R-R-intervals and with baroreflex sensitivity. Conclusions: The Leu7Pro polymorphism of preproNPY is related to decreased level of basal sympathetic activity, decreased insulin secretion, and delayed ghrelin suppression during oral glucose tolerance test. The increased responsiveness of autonomic functions to NE associated with the polymorphism may be connected to increased cardiovascular vulnerability.

scholarly journals Interplay of Dinner Timing and MTNR1B Type 2 Diabetes Risk Variant on Glucose Tolerance and Insulin Secretion: A Randomized Crossover Trial

Diabetes Care ◽  
2022 ◽  
Author(s):  
Marta Garaulet ◽  
Jesus Lopez-Minguez ◽  
Hassan S. Dashti ◽  
Céline Vetter ◽  
Antonio Miguel Hernández-Martínez ◽  
...  
Keyword(s):  
Type 2 Diabetes ◽  
Insulin Secretion ◽  
Glucose Tolerance ◽  
Cell Function ◽  
Insulin Response ◽  
Area Under The Curve ◽  
Oral Glucose ◽  
Elevated Concentration ◽  
Endogenous Melatonin

OBJECTIVE We tested whether the concurrence of food intake and elevated concentration of endogenous melatonin, as occurs in late eating, results in impaired glucose control, in particular in carriers of the type 2 diabetes–associated G allele in the melatonin receptor-1b gene (MTNR1B). RESEARCH DESIGN AND METHODS In a Spanish natural late-eating population, a randomized, crossover study was performed. Each participant (n = 845) underwent two evening 2-h 75-g oral glucose tolerance tests following an 8-h fast: an early condition scheduled 4 h prior to habitual bedtime (“early dinner timing”) and a late condition scheduled 1 h prior to habitual bedtime (“late dinner timing”), simulating an early and a late dinner timing, respectively. Differences in postprandial glucose and insulin responsesbetween early and late dinner timing were determined using incremental area under the curve (AUC) calculated by the trapezoidal method. RESULTS Melatonin serum levels were 3.5-fold higher in the late versus early condition, with late dinner timing resulting in 6.7% lower insulin AUC and 8.3% higher glucose AUC. In the late condition, MTNR1B G-allele carriers had lower glucose tolerance than noncarriers. Genotype differences in glucose tolerance were attributed to reductions in β-cell function (P for interaction, Pint glucose area under the curve = 0.009, Pint corrected insulin response = 0.022, and Pint Disposition Index = 0.018). CONCLUSIONS Concurrently high endogenous melatonin and carbohydrate intake, as typical for late eating, impairs glucose tolerance, especially in MTNR1B G-risk allele carriers, attributable to insulin secretion defects.

scholarly journals Identification of insulin secretory defects and insulin resistance during oral glucose tolerance test in a cohort of cystic fibrosis patients

2011 ◽  
Vol 165 (1) ◽  
pp. 69-76 ◽  
Author(s):  
A Battezzati ◽  
A Mari ◽  
L Zazzeron ◽  
G Alicandro ◽  
L Claut ◽  
...  
Keyword(s):  
Insulin Secretion ◽  
Insulin Sensitivity ◽  
Glucose Tolerance ◽  
Glucose Tolerance Test ◽  
Cell Function ◽  
Tolerance Test ◽  
Oral Glucose ◽  
Oral Glucose Tolerance ◽  
Β Cell ◽  
Β Cell Function

BackgroundCystic fibrosis (CF)-related diabetes is a leading complication of CF and is associated with pulmonary and nutritional deterioration, years before an evident hyperglycemia, possibly because of insulin deficiency and resistance.AimTo evaluate glucose tolerance, insulin secretion, and insulin sensitivity by a widely applicable method suitable for accurate and prospective measurements in a CF population.MethodsA total of 165 CF subjects (80 females) aged 17±5 years and 18 age- and sex-matched healthy controls (CON) received an oral glucose tolerance test with glucose, insulin and C-peptide determinations. Insulin sensitivity was defined on the basis of glucose and insulin concentrations using the oral glucose insulin sensitivity index, whereas β-cell function was determined on the basis of a model relating insulin secretion (C-peptide profile) to glucose concentration.ResultsFifteen percent of CF patients had glucose intolerance and 6% had diabetes without fasting hyperglycemia and 3% had diabetes with fasting hyperglycemia. β-cell function was reduced in CF patients compared with CON (70.0±4.1 vs 117.9±11.6 pmol/min per m2 per mM, P<0.001) and decreased significantly with age by −2.7 pmol/min per m2 per mM per year (confidence interval (CI) −4.5 to −0.82), i.e. almost 4% yearly. The early insulin secretion index was also reduced. Insulin sensitivity was similar to CON. CF patients who attained glucose tolerance comparable to CON had lower β-cell function and higher insulin sensitivity.ConclusionThe major alteration in insulin secretion and insulin sensitivity of CF patients is slowly declining β-cell function, consisting of delayed and reduced responsiveness to hyperglycemia, that in CF patients with normal glucose tolerance may be compensated by an increased insulin sensitivity.

scholarly journals Hypoglycemia and Islet Dysfunction Following Oral Glucose Tolerance Testing in Pancreatic-Insufficient Cystic Fibrosis

2020 ◽  
Vol 105 (10) ◽  
pp. 3179-3189
Author(s):  
Marissa J Kilberg ◽  
Clea Harris ◽  
Saba Sheikh ◽  
Darko Stefanovski ◽  
Marina Cuchel ◽  
...  
Keyword(s):  
Cystic Fibrosis ◽  
Insulin Secretion ◽  
Glucose Tolerance ◽  
Early Phase ◽  
Oral Glucose ◽  
Oral Glucose Tolerance ◽  
Insulin Effect ◽  
Secretory Rate ◽  
C Peptide ◽  
Islet Dysfunction

Abstract Context Oral glucose tolerance test (OGTT)-related hypoglycemia is common in pancreatic-insufficient cystic fibrosis (PI-CF), but its mechanistic underpinnings are yet to be established. Objective To delineate the mechanism(s) underlying OGTT-related hypoglycemia. Design and Setting We performed 180-minute OGTTs with frequent blood sampling in adolescents and young adults with PI-CF and compared results with those from a historical healthy control group. Hypoglycemia (Hypo[+]) was defined as plasma glucose &lt;65 mg/dL. We hypothesized that CF-Hypo[+] would demonstrate impaired early phase insulin secretion and persistent late insulin effect compared with control-Hypo[+], and explored the contextual counterregulatory response. Main Outcome Measure OGTT 1-hour and nadir glucose, insulin, C-peptide, and insulin secretory rate (ISR) incremental areas under the curve (AUC) between 0 and 30 minutes (early) and between 120 and 180 minutes (late), and Δglucagon120-180min and Δfree fatty acids (FFAs)120-180min were compared between individuals with CF and control participants with Hypo[+]. Results Hypoglycemia occurred in 15/23 (65%) patients with CF (43% female, aged 24.8 [14.6-30.6] years) and 8/15 (55%) control participants (33% female, aged 26 [21-38] years). The CF-Hypo[+] group versus the control-Hypo[+] group had higher 1-hour glucose (197 ± 49 vs 139 ± 53 mg/dL; P = 0.05) and lower nadir glucose levels (48 ± 7 vs 59 ± 4 mg/dL; P &lt; 0.01), while insulin, C-peptide, and ISR-AUC0-30 min results were lower and insulin and C-peptide, and AUC120-180min results were higher (P &lt; 0.05). Individuals with CF-Hypo[+] had lower Δglucagon120-180min and ΔFFA120-180min compared with the control-Hypo[+] group (P &lt; 0.01). Conclusions OGTT-related hypoglycemia in PI-CF is associated with elevated 1-hour glucose, impaired early phase insulin secretion, higher late insulin exposure, and less increase in glucagon and FFAs. These data suggest that hypoglycemia in CF is a manifestation of islet dysfunction including an impaired counterregulatory response.

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