Participants with type 1 diabetes had higher endogenous glucose production than controls (EGP; 5.9 ± 2.2 μmol/kg fat free mass [FFM]/min and 3.6 ± 1.7 μmol/kgFFM/min respectively; p = 0.0002) and higher non-esterified fatty acids (NEFA) in the low-dose phase (0.08 ± 0.01 mmol/L and 0.02 ± 0.02 mmol/L respectively; p = 0.001), indicating impaired insulin-mediated suppression of hepatic glucose release and lipolysis, respectively. Here, INS is linked to type 1 diabetes mellitus.