Evaluate the collective function of references cited together in a given text segment.
Classify their combined role into one of the following categories: 'method', 'background', or 'result'.

Text:Two studies using direct measurements by hyperinsulinemic euglycemic clamp reported that intrauterine growth restriction or low birth weight decreased the insulin sensitivity of whole body glucose uptake in young adult men and women combined (17) or of glycolysis, although not whole body glucose uptake in young adult men (18).
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