White rice was associated with type 2 diabetes in Chinese and Japanese populations.

A systematic review of observational studies reported that Chinese and Japanese people who eat more white rice were more likely to develop type 2 diabetes.

Clinical question:

Is consumption of white rice associated with the risk of developing type 2 diabetes?

The reviewers looked for prospective observational studies that recruited non-diabetic participants and followed them over time to see if they developed type 2 diabetes.

The evidence:

The reviewers found four studies that reported rice consumption in relation to diabetes risk.  352,384 patients were included, and 13,284 cases of diabetes arose during follow-up, which ranged from four to 22 years.

When the data from the different studies were combined, they showed that Asian (Chinese and Japanese) populations who ate the most white rice had a relative risk of 1.55 (95% confidence interval 1.20 to 2.01)  for developing type 2 diabetes when compared to those who ate the least.

The difference was not statistically significant among Western populations.  The Asian populations consumed significantly more white rice than the Western ones.

Appraisal hints:

Users of this research should consider:

  • Possible confounding.  Consumption of white rice may be acting as a marker of some other factor, such as low socioeconomic status.
  • Did the reviewers do enough to assess the likelihood of bias in the individual studies?
  • Were they sufficiently similar to merit combining in an overall measure?  The studies were conducted in very different populations with a very different rate of white rice consumption.
  • There was some evidence of inconsistency between the results of individual studies, and not enough studies to rule out statistical heterogeneity.
  • Some of the studies relied upon self-reports to establish diabetes outcomes.
  • These relative risks need to be considered in the context of baseline absolute risk and the amount of rice consumed by a particular population.  While the review provides information about the amount of rice consumed, and how this was measured in each study, it does not address the baseline risk of diabetes between each study, it only provides relative risks.
  • There is no data from this research about brown rice, which is thought to have a preventive effect.

Reference

The full text of this paper can be found on the BMJ website:

Hu A, Pan A et al.  White rice consumption and risk of type 2 diabetes: meta-analysis and systematic review.  BMJ 2012;344:e1454

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Badenoch

Badenoch
I am an information scientist with an interest in making knowledge from systematic research more accessible to people who need it. This means you. I've been attempting this in the area of Evidence-Based Health Care since 1995. So far the results have been mixed. For some reason we expected busy clinicians to search databases and appraise papers instead of seeing patients. We also expected publishers to make the research freely available to the people who paid for it.. Ha! Hence The National Elf service.

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