Substituting brown rice for white rice on diabetes risk factors in India: a randomised controlled trial.

India has the second largest number of people with type 2 diabetes (T2D) globally. Epidemiological evidence indicates that consumption of white rice is positively associated with T2D risk, while intake of brown rice is inversely associated. Thus, we explored the effect of substituting brown rice for white rice on T2D risk factors among adults in urban South India. A total of 166 overweight (BMI ≥ 23 kg/m2) adults aged 25-65 years were enrolled in a randomised cross-over trial in Chennai, India. Interventions were a parboiled brown rice or white rice regimen providing two ad libitum meals/d, 6 d/week for 3 months with a 2-week washout period. Primary outcomes were blood glucose, insulin, glycosylated Hb (HbA1c), insulin resistance (homeostasis model assessment of insulin resistance) and lipids. High-sensitivity C-reactive protein (hs-CRP) was a secondary outcome. We did not observe significant between-group differences for primary outcomes among all participants. However, a significant reduction in HbA1c was observed in the brown rice group among participants with the metabolic syndrome (-0·18 (se 0·08) %) relative to those without the metabolic syndrome (0·05 (se 0·05) %) (P-for-heterogeneity = 0·02). Improvements in HbA1c, total and LDL-cholesterol were observed in the brown rice group among participants with a BMI ≥ 25 kg/m2 compared with those with a BMI < 25 kg/m2 (P-for-heterogeneity < 0·05). We observed a smaller increase in hs-CRP in the brown (0·03 (sd 2·12) mg/l) compared with white rice group (0·63 (sd 2·35) mg/l) (P = 0·04). In conclusion, substituting brown rice for white rice showed a potential benefit on HbA1c among participants with the metabolic syndrome and an elevated BMI. A small benefit on inflammation was also observed.

Insulin resistance precedes weight loss in adults without diabetes : the Rancho Bernardo Study.

Insulin resistance is closely associated with both aging and overweight; yet in old age, weight loss is common, although insulin resistance increases. To study this paradox, the authors evaluated the role of insulin resistance in weight change among older adults from the Rancho Bernardo Study cohort. Participants were 725 nondiabetic men and women who were aged 50-89 years when weight and insulin were measured at baseline (1984-1987). The participants were evaluated again in 1992-1996, at which time weight was remeasured. Fasting insulin and homeostasis model assessment (HOMA) measurements were evaluated in separate but parallel statistical models as surrogates for insulin resistance. Insulin resistance, when defined as the top quartile of fasting insulin level or HOMA value, was significantly associated with weight loss before and after adjustment for baseline weight and age (fasting insulin: beta = -1.30 kg, p = 0.01; HOMA: beta = -1.18 kg, p = 0.01). Results were the same for men versus women, for the overweight (body mass index (weight (kg)/height (m)(2)) > 26.6) [corrected] versus the normal weight (body mass index < or = 26.6) [corrected], and for younger persons (age <70 years) versus older persons (age > or = 70 years). Insulin-resistant individuals had a threefold increased likelihood of losing 10 or more kg compared with those without insulin resistance. The authors conclude that hyperinsulinemia, independently of age and baseline weight, may have a catabolic effect in the elderly.