Recombinant human insulin via E. coli/yeast; subcutaneous injection preferred, IV for emergencies, pump for basal/bolus delivery; onset/duration varies by preparation.

Inhaled form only for Type 2; hepatic extraction makes C-peptide irrelevant.

Produced via oral tablets; degraded by insulin protease in the GI tract for rapid absorption.

Degraded minimally in the kidney; contraindicated in renal insufficiency without dose adjustment.

Long-acting only; physical activity shortens duration without site rotation.