Another Novolog -- Humalog Question

My PCP changed me from Novolog to Humalog yesterday. Wanted me to use a sliding scale. I refuse to do that. I have been bolusing for correx and for carbs for almost 7 or 8 years and I refuse to go back to an antiquated treatment regime.

This morning I did my fasting test at about 7:15. My BG was 401. Not sure why. My correx ratio is 1:20 and my fasting target is 100, so I took 15u of Humalog. At 8:22 I checked again and my BG was down to 277. At 10:20 I checked again and it was down to 53! What scared me was I didn’t have the usual signs of a low. Usually at 70 I start to shake. So what’s up with this??

I guess what I want to know is if lows are typical with Humalog.? What did I do wrong?

Here’s a snippet from a good synopsis of Humalog vs Novolog at 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.

Thanks Janet. I am going to read the article but what you posted is just the reverse of what happened to me since I went from novolog to Humalog.

I have to disagree with Janet in that the ONLY consistent finding is that how quickly a given insulin works is going to be an INDIVIDUAL experience that will not necessarily be what a particular study reveals.

Keep in mind that all clinical trials for insulin products are conducted on both patients with type 1 and type 2 diabetes and typically are split 50/50, which satisfies the FDA’s requirements but is not necessarily ideal to determine “average time-activity profiles” that appear in the FDA-mandated package insert and claim they are applicable to everyone. Dave is 100% correct in that lows are not unique to any particular insulin, however, the time-activity profile can have a significant impact on whether you experience a low, and you will likely need to titrate your own dosage when switching and make necessary adjustments. While an insurance company may have a “preferred” brand formulary, the FDA advises that all changes to insulin be done only under medical supervision, and your doctor should have been assisting to make the adjustment as easy as possible – I am surprised that you were not given better instructions to smooth the transition while minimizing the number of lows – your doctor should be reprimanded for failure to do so! My suggestion would be contact your doctor and tell them immediately what your experience has been since switching insulins, and request his/her assistance to make adjustments required. A good diabetes educator can also assist in this, and in some cases, may actually be far more helpful than a doctor.