medwireNews: Risk alleles for type 2 diabetes influence the risk for women developing the condition after experiencing gestational diabetes, say researchers.
The findings came from an analysis of two independent cohorts – 1884 women with gestational diabetes from the US Nurses’ Health Study and 550 from the Danish National Birth Cohort. These women were followed up for an average of 21.3 and 12.7 years, respectively, during which time 23.7% and 28.2% developed type 2 diabetes.
The researchers constructed a genetic risk score for type 2 diabetes based on 59 single nucleotide polymorphisms (SNPs) and found that each additional five risk alleles increased women’s type 2 diabetes risk by 7% in the US cohort and 9% in the Danish cohort.
“To our knowledge, this is the first study examining a set of candidate SNPs in relation to the risk of [type 2 diabetes] in women with a history of [gestational diabetes],” say Cuilin Zhang (Eunice Kennedy Shriver National Institute of Child Health and Human Development, Bethesda, Maryland, USA) and study co-authors.
“Future studies of larger size are needed, which may require consortium efforts, they write in BMJ Open Diabetes Research & Care.”
But the team adds: “The magnitude of association, however, was modest.”
Of the SNPs considered, just 11 were significantly associated with diabetes in the pooled analysis, and these lost significance after correction for false-discovery rate. Eight of the 11 SNPs were positively associated with diabetes, most of which have a role in beta-cell function, and three were negatively associated.
The researchers also uncovered some evidence for a protective effect of a healthy diet, which was seen in both cohorts. In the US cohort, for example, each additional five risk alleles increased women’s type 2 diabetes risk by 13% among those with poor dietary quality after pregnancy (assessed with a semiquantitative food frequency questionnaire), whereas genetic risk had no significant effect in women with a healthy diet.
The effect of risk alleles in women with a poor diet was not statistically significantly greater than in those with a healthy diet (ie, the interaction was not significant), but Zhang and team believe that this “suggestive evidence” that a healthy diet might help to counteract genetic risk “supports public health efforts of encouraging a healthful diet” to reduce the risk for type 2 diabetes in this high-risk population.
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