Comparison of a carbohydrate-free diet vs. fasting on plasma glucose, insulin and glucagon in type 2 diabetes

Frank Q. Nuttall, Rami M. Almokayyad, Mary C. Gannon

Research output: Contribution to journalArticlepeer-review

23 Scopus citations

Abstract

Objective. Hyperglycemia improves when patients with type 2 diabetes are placed on a weight-loss diet. Improvement typically occurs soon after diet implementation. This rapid response could result from low fuel supply (calories), lower carbohydrate content of the weight-loss diet, and/or weight loss per se. To differentiate these effects, glucose, insulin, C-peptide and glucagon were determined during the last 24 h of a 3-day period without food (severe calorie restriction) and a calorie-sufficient, carbohydrate-free diet. Research design Seven subjects with untreated type 2 diabetes were studied. A randomized-crossover design with a 4-week washout period between arms was used. Methods. Results from both the calorie-sufficient, carbohydrate-free diet and the 3-day fast were compared with the initial standard diet consisting of 55% carbohydrate, 15% protein and 30% fat. Results. The overnight fasting glucose concentration decreased from 196 (standard diet) to 160 (carbohydrate-free diet) to 127 mg/dl (fasting). The 24 h glucose and insulin area responses decreased by 35% and 48% on day 3 of the carbohydrate-free diet, and by 49% and 69% after fasting. Overnight basal insulin and glucagon remained unchanged. Conclusions. Short-term fasting dramatically lowered overnight fasting and 24 h integrated glucose concentrations. Carbohydrate restriction per se could account for 71% of the reduction. Insulin could not entirely explain the glucose responses. In the absence of carbohydrate, the net insulin response was 28% of the standard diet. Glucagon did not contribute to the metabolic adaptations observed.

Original languageEnglish (US)
Pages (from-to)253-262
Number of pages10
JournalMetabolism: clinical and experimental
Volume64
Issue number2
DOIs
StatePublished - Feb 1 2015

Bibliographical note

Funding Information:
Supported in part by Merit Review Funds from the Department of Veterans Affairs . The Department of Veterans Affairs had no involvement in study design, collection, analysis and interpretation of data, writing of the report or decision to submit the article for publication.

Funding Information:
Supported in part by funds from the Department of Veterans Affairs . The Department of Veterans Affairs had no involvement in the study design, the collection, analysis and interpretation of data, in the writing of the manuscript or in the decision to submit the manuscript for publication.

Publisher Copyright:
© 2015 Elsevier Inc. All rights reserved.

Copyright:
Copyright 2015 Elsevier B.V., All rights reserved.

Keywords

  • Carbohydrate
  • Circadian rhythm
  • Diabetes
  • Diet
  • Fasting

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