With regard to fruit and vegetables, prospective studies have so far produced quite inconsistent results when evaluating the risk to develop type 2 diabetes. This might in part be due to measurement error involved in the assessment of dietary intake.

One study in this issue used a quite unique approach to, at least in part, overcome this limitation. Dietary intake was assessed using a prospective 7-day food diary and thus allowed to estimate absolute intake of fruit and vegetables. However, even more interesting than the observed protective effect of higher total intake of fruit and vegetables is the observation that – independent of the quantity – a higher variety of fruit and vegetables consumed seems to reduce diabetes risk.

The second study in this issue deals with gestational diabetes, a common complication of pregnancy affecting increasing proportions of childbearing women. Women with gestational diabetes have an increased risk of type 2 diabetes in later years, however, gestational diabetes has severe effects on the offspring as well. Despite its potential importance there has been little research to the question whether diet before pregnancy is related to risk of gestational diabetes. The study adds valuable information indicating that consumption of fruit juices in moderate amounts might be beneficial, despite the relatively high sugar contents of juices.

The third study in this issue compares macro-level data on food availability and other societal measures with the prevalence of diabetes across countries. Higher availability of fruits and vegetables was related to lower prevalence rates after accounting for other risk factors. However, such data need to be treated quite cautiously given that prevalence rates of diabetes, and of many societal measures, are not collected in comparable time periods nor quality across the globe. Furthermore, macro-level studies are prone to ecological fallacy and results need to be seen to be indicative rather than confirmatory. Still, while there has been considerable effort to explain risk of diabetes within populations, more research is needed to answer what explains the large differences in diabetes prevalence between populations.

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