A Randomised Four-Intervention Crossover Study Investigating the Effect of Carbohydrates on Daytime Profiles of Insulin, Glucose, Non-Esterified Fatty Acids and Triacylglycerols in Middle-Aged Men

Br J Nutr. 2003 Feb;89(2):207-18. doi: 10.1079/BJN2002769.

Abstract

Postprandial concentrations of glucose, insulin and triacylglycerols (TG) correlate to risk for CHD. Carbohydrates affect many metabolites that could have a potential effect on cardiovascular risk factors. The objective of the present study was to examine, using a randomised prospective study, the acute (day 1) and ad libitum medium-term (day 24) effects of four diets: a high-fat diet (HIGH-FAT; 50 % fat, >34 % monounsaturated fatty acids); a low-glycaemic index (GI) diet (LOW-GI; high-carbohydrate, low-GI); a high-sucrose diet (SUCROSE; high carbohydrate increase of 90 g sucrose/d); a high-GI diet (HIGH-GI; high-carbohydrate, high-GI). Daytime profiles (8 h) (breakfast, lunch and tea) of lipid and carbohydrate metabolism were completed during day 1 and day 24. Seventeen middle-aged men with one or more cardiac risk factors completed the study. There was no change from day 1 or between diets in fasting glucose, lipids or homeostatic assessment model (HOMA) on day 24. The HIGH-FAT compared with the three high-carbohydrate diets was associated with lower postprandial insulin and glucose but higher postprandial TG and non-esterified fatty acids (NEFA). There was a significant increase in the 6 h (15.00 hours) TG concentration (day 1, 2.6 (sem 0.3) mmol/l v. day 24, 3.3 (sem 0.3) mmol/l; P<0.01) on the SUCROSE diet. Postprandial HOMA (i.e. incremental area under the curve (IAUC) glucose (mmol/l per min)xIAUC insulin/22.5 (mU/l per min)) median changes from day 1 to day 24 were -61, -43, -20 and +31 % for the HIGH-FAT, LOW-GI, SUCROSE and HIGH-GI diets respectively. The HIGH-GI percentage change was significantly different from the other three diets (P<0.001). Despite being advised to maintain an identical energy intake there was a significant weight change (-0.27 (sem 0.3) kg; P<0.02) on the LOW-GI diet compared with the SUCROSE diet (+0.84 (sem 0.3) kg). In conclusion the HIGH-FAT diet had a beneficial effect on postprandial glucose and insulin over time but it was associated with higher postprandial concentrations of TG and NEFA. Conversely the HIGH-GI diet appeared to increase postprandial insulin resistance over the study period.

Publication types

  • Clinical Trial
  • Randomized Controlled Trial
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Area Under Curve
  • Blood Glucose / analysis*
  • Cross-Over Studies
  • Dietary Carbohydrates / administration & dosage*
  • Dietary Fats / administration & dosage
  • Fatty Acids, Nonesterified / blood*
  • Glycemic Index
  • Humans
  • Insulin / blood*
  • Insulin Resistance
  • Male
  • Middle Aged
  • Postprandial Period
  • Prospective Studies
  • Risk Factors
  • Time Factors
  • Triglycerides / blood*

Substances

  • Blood Glucose
  • Dietary Carbohydrates
  • Dietary Fats
  • Fatty Acids, Nonesterified
  • Insulin
  • Triglycerides