Type of insulin	Onset of action	Peak of action	Duration of action	Cost per vial for brand name insulin (generic insulin)*	Common pitfalls
Insulin lispro (Humalog)	5 to 15 minutes	1 to 2 hours	4 to 5 hours	$ 28	Hypoglycemia occurs if the lag time is too long or the patient exercises within one hour of administration; with high-fat meals, the dose should be adjusted downward.
Regular insulin (Humulin R)	30 to 60 minutes	2 to 4 hours	6 to 8 hours	22 (21)	Lag time is not used appropriately; the insulin should be given 20 to 30 minutes before the patient eats.
NPH insulin (Humulin N)	1 to 3 hours	5 to 7 hours	13 to 18 hours	22 (19 to 21)	In many patients, breakfast injection does not last until the evening meal; administration with the evening meal does not meet insulin needs on awakening.
Lente insulin (Humulin L)	1 to 3 hours	4 to 8 hours	13 to 20 hours	22 (18 to 21)	Zinc suspension binds with regular insulin, which loses its effect if it is left in the syringe for more than a few minutes.
Ultralente insulin (Humulin U)	2 to 4 hours	8 to 14 hours	20 to 24 hours	22	Same as for lente insulin; in addition, peak of action is erratic in some patients.