CAROLYN JIMENEZ, PHD

OBJECTIVE — To compare insulin levels and actions in patients with type 1 diabetes after subcutaneous injection of the rapid-acting insulin analogs aspart and lispro. RESEARCHDESIGNANDMETHODS — Seven C-peptide–negative patients with type 1 diabetes (two men and five women) were studied at the General Clinical Research Center at Temple University Hospital two times, 1 month apart. Their plasma glucose was normalized overnight by intravenous infusion of insulin. The next morning, they received subcutaneous injections of either aspart or lispro (9.4 1.9 U) in random order. For the next 4–5 h, their plasma glucose was clamped at5.5 mmol/l with a variable infusion of 20 % glucose. The study was terminated after 8 h. RESULTS — Both insulin analogs produced similar serum insulin levels (250–300 pmol/l) at 30 min and disappeared from serum after4 h. Insulin aspart and lispro had similar effects on glucose and fat metabolism. Effects on carbohydrate metabolism (glucose uptake, glucose oxi-dation, and endogenous glucose production) peaked after2–3 h and disappeared after5–6 h. Effects on lipid metabolism (plasma free fatty acid, ketone body levels, and free fatty acid oxidation) appeared to peak earlier (at2 h) and disappeared earlier (after4 h) than the effect