Here’s a snippet from a good synopsis of Humalog vs Novolog at http://www.diabetesnet.com/diabetes_treatments/insulin_humalog.php. If you’re pumping, that may be a big factor.
Differences Between Humalog Versus Novolog
A couple of major differences are being reported by users between Novolog and Humalog. Especially among pumpers who switch from Humalog to Novolog, reports have surfaced that Novolog appears to be both stronger and quicker than Humalog, and doses have to be cut in order to prevent hypoglycemia. Dose reductions are often in the 10% range, and it may be wise to reduce doses right away to prevent unwanted lows. If, instead, blood sugars rise, doses can always be raised again.
Novolog also starts working faster than Humalog. Although no direct comparison of Novolog and Humalog has been reported, one research study found that in normal individuals, Novolog reaches peak activity at 52 minutes, compared to 145 minutes (2 hours and 25 minutes) for Regular insulin. Humalog peaks at about 75 minutes (Eur J Clin Pharmacol 1999 May;55(3):199-203). Both pumpers and injectors may note lower post-meal readings due to the faster onset of action.
The clearly defined action times of the fast insulin makes it easier to troubleshoot problems. For information on how to determine the number of carbs covered by each unit, see the 500 Rule in the Pocket Pancreas. Humalog and Novolog are also excellent for lowering high blood sugars with less time spent at high blood sugar levels, and less residual insulin left to trigger low blood sugars later. For information on how to safely lower highs, see the 1800 Rule, also in the Pocket Pancreas.