Meal glucose (A and B), insulin (C and D), C-peptide (E and F), proinsulin (G and H), and glucagon (I and J) concentrations in people with normal fasting glucose and normal glucose tolerance and in people with impaired fasting glucose and impaired glucose tolerance. Concentrations are shown during the meal after saline infusion (○ or in the case of IFG/IGT Δ), Intralipid and glucose infusion (•), and during insulin infusion (▴).