Objective: Preterm infants are at risk of developing insulin resistance. It is not known whether insulin resistance in adult life is different between those with a low weight at term (preterm growth restraint, PGR) and those with a normal weight at term. Study Design: Insulin sensitivity, measured by the hyperinsulinemic euglycemic clamp, was investigated in 21-year-old adults born very preterm (i.e. <32 gestational weeks), of whom 17 were small for gestational age (SGA), 12 were appropriate for gestational age with PGR (AGA-PGR) and 28 were AGA-non-PGR. Results: Insulin sensitivity expressed as M value (glucose disposal mg/kg/min) was lower in AGA-non-PGR (8.9) than in SGA (11.0) or AGA-PGR subjects (10.4). These differences disappeared after adjustment for current body size. Linear growth between 3 months and 21 years of age was different between AGA-non-PGR and SGA subjects and between AGA-nonPGR subjects and the combined AGA-PGR and SGA subjects. Conclusion: In young adults born very preterm, differences in insulin sensitivity between those born SGA, with PGR and without PGR are related to the current body composition. Copyright © 2011 S. Karger AG, Basel.