scholarly journals Reduced Glucose Tolerance and Skeletal Muscle GLUT4 and IRS1 Content in Cyclists Habituated to a Long-Term Low-Carbohydrate, High-Fat Diet

2020 ◽  
Vol 30 (3) ◽  
pp. 210-217
Author(s):  
Christopher C. Webster ◽  
Kathryn M. van Boom ◽  
Nur Armino ◽  
Kate Larmuth ◽  
Timothy D. Noakes ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Glucose Tolerance ◽  
Glucose Tolerance Test ◽  
Tolerance Test ◽  
Oral Glucose ◽  
Mixed Diet ◽  
Oral Glucose Tolerance ◽  
High Fat ◽  
Low Carbohydrate

Very little is known about how long-term (>6 months) adaptation to a low-carbohydrate, high-fat (LCHF) diet affects insulin signaling in healthy, well-trained individuals. This study compared glucose tolerance; skeletal muscle glucose transporter 4 (GLUT4) and insulin receptor substrate 1 (IRS1) content; and muscle enzyme activities representative of the main energy pathways (3-hydroxyacetyl-CoA dehydrogenase, creatine kinase, citrate synthase, lactate dehydrogenase, phosphofructokinase, phosphorylase) in trained cyclists who followed either a long-term LCHF or a mixed-macronutrient (Mixed) diet. On separate days, a 2-hr oral glucose tolerance test was conducted, and muscle samples were obtained from the vastus lateralis of fasted participants. The LCHF group had reduced glucose tolerance compared with the Mixed group, as plasma glucose concentrations were significantly higher throughout the oral glucose tolerance test and serum insulin concentrations peaked later (LCHF, 60 min; Mixed, 30 min). Whole-body insulin sensitivity was not statistically significantly different between groups (Matsuda index: LCHF, 8.7 ± 3.4 vs. Mixed, 12.9 ± 4.6; p = .08). GLUT4 (LCHF: 1.13 ± 0.24; Mixed: 1.44 ± 0.16; p = .026) and IRS1 (LCHF: 0.25 ± 0.13; Mixed: 0.46 ± 0.09; p = .016) protein content was lower in LCHF muscle, but enzyme activities were not different. We conclude that well-trained cyclists habituated to an LCHF diet had reduced glucose tolerance compared with matched controls on a mixed diet. Lower skeletal muscle GLUT4 and IRS1 contents may partially explain this finding. This could possibly reflect an adaptation to reduced habitual glucose availability rather than the development of a pathological insulin resistance.

scholarly journals Direct Measurements of the Permeability Surface Area for Insulin and Glucose in Human Skeletal Muscle

2003 ◽  
Vol 88 (10) ◽  
pp. 4559-4564 ◽  
Author(s):  
Soffia Gudbjörnsdóttir ◽  
Mikaela Sjöstrand ◽  
Lena Strindberg ◽  
John Wahren ◽  
Peter Lönnroth
Keyword(s):  
Skeletal Muscle ◽  
Blood Flow ◽  
Glucose Tolerance ◽  
Plasma Insulin ◽  
Glucose Tolerance Test ◽  
Tolerance Test ◽  
Oral Glucose ◽  
Oral Glucose Tolerance ◽  
Permeability Surface ◽  
One Step

Abstract To elucidate mechanisms regulating capillary transport of insulin and glucose, we directly calculated the permeability surface (PS) area product for glucose and insulin in muscle. Intramuscular microdialysis in combination with the forearm model and blood flow measurements was performed in healthy males, studied during an oral glucose tolerance test or during a one-step or two-step euglycemic hyperinsulinemic clamp. PS for glucose increased significantly from 0.29 ± 0.1 to 0.64 ± 0.2 ml/min·100 g after oral glucose tolerance test, and glucose uptake increased from 1.2 ± 0.4 to 2.6 ± 0.6 μmol/min·100 g (P < 0.05). During one-step hyperinsulinemic clamp (plasma insulin, 1.962 pmol/liter), PS for glucose increased from 0.2 ± 0.1 to 2.3 ± 0.9 ml/min·100 g (P < 0.05), and glucose uptake increased from 0.6 ± 0.2 to 5.0 ± 1.4 μmol/min·100 g (P < 0.05). During the two-step clamp (plasma insulin, 1380 ± 408 and 3846 ± 348 pmol/liter), the arterial-interstitial difference and PS for insulin were constant. The PS for glucose tended to increase (P = not significant), whereas skeletal muscle blood flow increased from 4.4 ± 0.7 to 6.2 ± 0.8 ml/min·100 ml (P < 0.05). The present data show that PS for glucose is markedly increased by oral glucose, whereas a further vasodilation exerted by high insulin concentrations may not be physiologically relevant for capillary delivery of either glucose or insulin in resting muscle.

No influence of high- and low-carbohydrate diet on the oral glucose tolerance test in pregnancy

2004 ◽  
Vol 37 (4) ◽  
pp. 323-327 ◽  
Author(s):  
Kai J Buhling ◽  
Eva Elsner ◽  
Christiane Wolf ◽  
Thomas Harder ◽  
Barbara Engel ◽  
...  
Keyword(s):  
Glucose Tolerance ◽  
Oral Glucose Tolerance Test ◽  
Glucose Tolerance Test ◽  
Tolerance Test ◽  
Oral Glucose ◽  
Oral Glucose Tolerance ◽  
Carbohydrate Diet ◽  
Low Carbohydrate Diet ◽  
Low Carbohydrate ◽  
In Pregnancy

Surgical outcome after repeated transsphenoidal surgery in acromegaly

1996 ◽  
Vol 85 (2) ◽  
pp. 239-247 ◽  
Author(s):  
Hélène Long ◽  
Hugues Beauregard ◽  
Maurice Somma ◽  
Ronald Comtois ◽  
Omar Serri ◽  
...  
Keyword(s):  
Glucose Tolerance ◽  
Oral Glucose Tolerance Test ◽  
Transsphenoidal Surgery ◽  
Glucose Tolerance Test ◽  
Tolerance Test ◽  
Oral Glucose ◽  
Oral Glucose Tolerance ◽  
Content Type ◽  
Fine Print

✓ Transsphenoidal selective adenomectomy is the most efficient primary treatment for acromegaly. However, management of persistent or recurrent disease remains controversial. The objective of the present study was to evaluate the early and long-term efficacy and safety of a second transsphenoidal surgery performed in those cases. The results of a retrospective study of 16 patients undergoing reoperation by the senior author (J.H.) between 1970 and 1991 are reported. Reoperation was performed for persistent or progressive acromegaly in 11 patients, visual impairment in four, and disease recurrence in one. Normalization of growth hormone (GH) was defined as a basal GH level of less than 5µg/L and suppression to less than 2 µg/L during the oral glucose tolerance test. Long-term follow-up data were available in 15 patients. The second transsphenoidal surgery induced a greater than 50% decrease of GH level in 11 patients. Three (19%) of 16 patients were cured according to the authors' criteria and remained so after 2, 7, and 20 years. Two more patients had a postoperative basal GH level of less than 5 µg/L but incomplete suppression during the oral glucose tolerance test. Thus, a total of five patients (31%) achieved a basal GH of less than 5 µg/L. One other patient who had no initial improvement after the second transsphenoidal surgery had spontaneous normalization of his GH level after 13 years. The following complications of the second surgery occurred in three patients: one subarachnoid hemorrhage, two new visual field defects, one cranial nerve palsy, and one meningitis. Moreover, 10 patients (62.5%) developed one or more new pituitary hormone deficiencies. In conclusion, reoperation for persistent or recurrent acromegaly has low success and high complication rates. According to the authors' experience, this procedure should be reserved for patients unresponsive to other forms of therapy or with progressive visual impairment despite medical therapy.

Effects of a single bout of aerobic exercise on short-term low-carbohydrate/high-fat intake-induced postprandial glucose metabolism during an oral glucose tolerance test

Metabolism ◽  
2013 ◽  
Vol 62 (10) ◽  
pp. 1406-1415 ◽  
Author(s):  
Shigeharu Numao ◽  
Hiroshi Kawano ◽  
Naoya Endo ◽  
Yuka Yamada ◽  
Masayuki Konishi ◽  
...  
Keyword(s):  
Glucose Tolerance Test ◽  
Postprandial Glucose ◽  
Tolerance Test ◽  
Oral Glucose ◽  
Fat Intake ◽  
Oral Glucose Tolerance ◽  
High Fat ◽  
Short Term ◽  
Low Carbohydrate ◽  
Single Bout
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