White rice consumption and risk of type 2 diabetes: meta-analysis and systematic review

Reply to Ady Oster et al.

25 April 2012

Dear Editor:
We read with interest Oster et al’s response and the table. However, we were puzzled by the data presented in this poorly-denoted table. We did not understand why adjusted means were not provided for all cells. Further, the 95% CIs did not necessarily include the means listed in the table. Nonetheless, in response to Oster et al’s concerns on the multivariate adjustments in the studies included in our meta-analysis,1 we want to emphasize that age and body mass index (BMI) were controlled for in all studies. In addition, a wide array of other variables was also adjusted in these studies. Besides the multivariate adjustments, the validity of the data was also underpinned by the prospective study design, use of validated questionnaires to assess diet, and high follow-up rate. On the contrary, we were concerned about the validity of Oster et al’s data. Given the positive correlations of age/BMI with rice intake and glucose levels, we shall anticipate that the inverse association between rice intake and fasting glucose would be strengthened after adjusting for age and BMI, but the opposite was shown in the table. In addition, Oster et al described that the correlation between BMI and fasting glucose was strong, which should be expected. However, the adjusted means were almost identical between overweight and obese participants.

Some key questions are yet to be addressed in this research. For example, more data are warranted to examine the effects of replacing white rice with brown rice on insulin resistance, and it is interesting to further explore the biological mechanisms underlying the association between white rice and diabetes risk.

1. Hu EA, Pan A, Malik V, Sun Q. White rice consumption and risk of type 2 diabetes: meta-analysis and systematic review. BMJ 2012;344:e1454.

Competing interests: None declared

Qi Sun, Nutritional Epidemiologist

Harvard School of Public Health; Brigham and Women's Hospital and Harvard Medical School, 665 Huntington Avenue, Boston, MA 02115, USA

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