Consumption of red and processed meat and refined grains for 4weeks decreases insulin sensitivity in insulin-resistant adults: A randomized crossover study.
BACKGROUND
Red and processed meat and refined grains are associated with an increased risk of type 2 diabetes. Interventions are limited. We hypothesized that a diet high in red and processed meat and refined grains (HMD) would decrease insulin sensitivity compared to a diet high in whole grains, nuts, dairy and legumes with no red meat (HWD).


METHODS
Forty-nine subjects without diabetes [15 men and 34 women, age, 35.6±15.7 years, body mass index (BMI), 27±5.9kg/m2] underwent two 4-week weight-stable dietary interventions in a randomized crossover design. The insulin sensitivity index (ISI) was calculated from the last 30min of a continuous low-dose insulin (25mU/kg·h) and glucose (4mg/kg·min) infusion test (LDIGIT120-150min) at the end of each diet.


RESULTS
The population fell into two very discrete groups: those with a very low insulin response in the LDIGIT120-150minon HMD (Group 1<56pmol/L, n=24), and those with relatively normal insulin responses (Group 2>56pmol/L, n=25). Group 2 had significantly higher insulin concentrations [(median and interquartile range) 153, 180 for HMD vs. 123, 149pmol/L for HWD; P=0.019] and glucose concentrations [(mean±standard deviation) 7.4±1.3 for HMD vs.6.7±1.2mmol/L for HWD; P=0.05], resulting in a significantly decreased ISI [(median and interquartile range) 21.1, 34.2 for HMD vs. 31.6, 39.4 for HWD; P=0.014] compared to HWD. Log ISI after HMD was significantly correlated with BMI (r=-0.5; P=0.009), fat mass (r=-0.55; P=0.004) and self-reported activity levels (r=-0.45; P=0.024).


CONCLUSIONS
A dietary pattern high in red and processed meat and refined grains decreased insulin sensitivity compared to a dietary pattern high in whole grains, nuts, dairy products and legumes only in relatively insulin-resistant adults.
School of Pharmacy and Medical Sciences, University of South Australia, Adelaide, Australia.
Yoona
Y
Kim
School of Pharmacy and Medical Sciences, University of South Australia, Adelaide, Australia.
Jennifer B
JB
Keogh
School of Pharmacy and Medical Sciences, University of South Australia, Adelaide, Australia. Electronic address: peter.clifton@unisa.edu.au.
Peter M
PM
Clifton
D050154:Adiposity; D000328:Adult; D001786:Blood Glucose / Q000378:metabolism; D015992:Body Mass Index; D018592:Cross-Over Studies; D003611:Dairy Products; D004032:Diet; D002523:Edible Grain / Q000009:adverse effects*; D015444:Exercise; D007887:Fabaceae; D005260:Female; D005951:Glucose Tolerance Test; D006801:Humans; D007333:Insulin Resistance; D008055:Lipids / Q000097:blood; D008297:Male; D008460:Meat / Q000009:adverse effects*; D008875:Middle Aged; D009754:Nuts
D001786:Blood Glucose; D008055:Lipids
Insulin sensitivity; Red and processed meat; Refined grains; Whole grains