Lifestyle Changes May Reverse Development of the Insulin Resistance Syndrome. The Oslo Diet and Exercise Study: a randomized trial

  1. P Urdal, MD
  1. Hormone Laboratory, Aker University Hospital Oslo, Norway
  2. Department of Biology and Sports Medicine, Norwegian University of Sport and Physical Education Oslo, Norway
  3. Department of Preventive Cardiology, Ullevaal University Hospital Oslo, Norway
  4. Life Insurance Companies’ Institute for Medical Statistics, Ullevaal University Hospital Oslo, Norway
  5. Department of Clinical Chemistry, Ullevaal University Hospital Oslo, Norway
  1. Address correspondence and reprint requests to Peter A. Torjesen, PhD, Hormone Laboratory, Aker University Hospital, N-0514 Oslo, Norway.

Abstract

OBJECTIVE To compare and assess the single and joint effect of diet and exercise intervention for 1 year on insulin resistance and the development leading toward the insulin resistance syndrome.

RESEARCH DESIGN AND METHODS An unmasked, randomized 2 × 2 factorial intervention trial was applied with a duration of 1 year for each participant. The trial comprised 219 men and women with diastolic blood pressure of 86–99 mmHg, HDL cholesterol < 1.20 mmol/l, triglycerides > 1.4 mmol/l, total cholesterol of 5.20–7.74 mmol/l, and BMI > 24 kg/m2. Participants were randomly allocated to diet group (n = 35), diet and exercise group (n = 67), exercise group (n = 54), and control group (n = 43). The diet included increased intake of fish and reduced total fat intake. The exercise program entailed supervised endurance exercise three times a week. Baseline cross-sectional changes and 1-year changes in insulin resistance, fasting serum levels of insulin, C-peptide, proinsulin, glucose, and lipids as well as weight, mean blood pressure, and plasminogen activator inhibitor 1 (PAI-1) values were recorded.

RESULTS The cross-sectional results at baseline showed significant correlations between the calculated insulin resistance and BMI (r = 0.54) and correlations between the mean blood pressure (mBP) (r = 0.26) and PAI-1 (r = 0.40). The 1-year diet intervention gave a significant decrease in the calculated insulin resistance from 4.6 to 4.2 and a positive correlation between the changes in insulin resistance and changes in BMI (r = 0.40). The diet and exercise intervention also led to significantly decreased insulin resistance (from 5.0 to 4.0). The exercise intervention did not significantly change insulin resistance.

CONCLUSIONS The cross-sectional and 1-year intervention results supported each other and underscored the important connection between increased BMI and the development leading toward the insulin resistance syndrome.

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