Intensive lifestyle changes are necessary to improve insulin sensitivity: a randomized controlled trial.
OBJECTIVE
The extent to which lifestyle must be altered to improve insulin sensitivity has not been established. This study compares the effect on insulin sensitivity of current dietary and exercise recommendations with a more intensive intervention in normoglycemic insulin-resistant individuals.


METHODS
Seventy-nine normoglycemic insulin-resistant (determined by the euglycemic insulin clamp) men and women were randomized to either a control group or one of two combined dietary and exercise programs. One group (modest level) was based on current recommendations and the other on a more intensive dietary and exercise program. Insulin sensitivity was measured using a euglycemic insulin clamp, body composition was measured using dual-energy X-ray absorptiometry, and anthropometry and aerobic fitness were assessed before and after a 4-month intervention period. Four-day dietary intakes were recorded, and fasting glucose, insulin, and lipids were measured.


RESULTS
Only the intensive group showed a significant improvement in insulin sensitivity (23% increase, P=0.006 vs. 9% in the modest group, P=0.23). This was associated with a significant improvement in aerobic fitness (11% increase in the intensive group, P=0.02 vs. 1% in the modest group, P=0.94) and a greater fiber intake, but no difference in reported total or saturated dietary fat.


CONCLUSIONS
Current clinical dietary and exercise recommendations, even when vigorously implemented, did not significantly improve insulin sensitivity; however, a more intensive program did. Improved aerobic fitness appeared to be the major difference between the two intervention groups, although weight loss and diet composition may have also played an important role in determining insulin sensitivity.
McAuley
Kirsten A
KA
Department of Human Nutrition, Otago University, Dunedin, New Zealand. kirsten.mcauley@stonebow.otago.ac.nz
Williams
Sheila M
SM
Mann
Jim I
JI
Goulding
Ailsa
A
Chisholm
Alex
A
Wilson
Noela
N
Story
Gretchen
G
McLay
Rebecca T
RT
Harper
Michelle J
MJ
Jones
Ianthe E
IE
D015502:Absorptiometry, Photon; D000328:Adult; D000368:Aged; D001786:Blood Glucose / Q000187:drug effects / Q000378:metabolism*; D001794:Blood Pressure / Q000187:drug effects; D001823:Body Composition; D015444:Exercise; D005260:Female; D015309:Glucose Clamp Technique; D006801:Humans; D007328:Insulin / Q000008:administration & dosage / Q000494:pharmacology*; D007333:Insulin Resistance; D008019:Life Style; D008297:Male; D008875:Middle Aged; D010101:Oxygen Consumption / Q000187:drug effects
D001786:Blood Glucose; D007328:Insulin