My daughter was diagnosed with T1D in 2009. She has only ever used Humalog. Now her insurance company says as of January 2026 Humalog will no longer be in their formulary so that she will have to switch to Novolog. Has anyone on the forum ever used one and then the other? And has it made any difference at all in terms of your diabetes management? In other words, is there any significant difference? I don’t know if it’s relevant but our daughter is quite insulin sensitive.
My ins has switched me back and forth between these two. For me, they’re mostly the same. I find Humalog to be slightly faster and with slightly less of a tail, but really no functional difference. They are different formulations though, so everyone can have a different experience
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There is a chemical difference I believe but some people switch and never have an issue. You might try it. Also look at the reaction times. I was allergic to Humalog so I had to get authorizations to not have to change.
I am more of a Humalog fan. As said already some never notice a difference. I have tried Novalog a few times for various reasons and Novalog was a little slower for me and I had more of a problem with dropping at night because of that. But plenty of people love Novalog.
Usually with insurance they will want you to try the Novalog and if it doesn’t work as well your doctor can put in an appeal for Humalog. Saying why your daughter needs it because etc. If that happens though the Humalog will be covered but usually under a higher tier cost, I don’t think the $35 is a cap when it isn’t one of the insulins covered under their regular formulary.
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I’ve been switched back and forth between the 2. I noticed not difference with MDI (multiple daily injections), but using a Tandem T:Slim X2 pump Humalog starts being less effective on day 3. This doesn’t happen with Novolog.
Tandem recommends to change cartridges after 2 days with Humalog. They don’t give reasons but it is probably interaction with the plastic bag that this system uses., most other pump systems use a rigid plastic reservoir.. It’s not an extreme effect, and probably most won’t notice. I tend to watch my numbers obsessively.
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@Luis3 I do remember reading somewhere that Humalog breaks down faster in plastic. It was in relation to it being used in Omnipods and sometimes switching to Novalog in the pods cleared up peoples problems. That was one of the times I tried Novalog to see if it helped my problem with pod/site failures. It didn’t matter for me, the sites failed just the same. I think @Eric2 is the one that is familiar with it.
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I use a pump and switched from Humalog to Novalog for insurance. Didn’t change my settings and experienced no noticeable change in my control.
I have experience with both Humalog and Novolog and notice no difference.
I’ve used both over the years and I don’t see any difference.
Humalog is made using RNA transcriptase using bacteria. Bacteria also produce tyramine, which many people react adversely to. Novolog is made using RNA transcriptase using fungi, which don’t product tyramine. Humalog make many people sick without knowing it.
John
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I was diagnosed type 1 as a young teen in 1973. (I am old. 
) Over the years i’ve had various forms. The only things that truly made a difference were getting an insulin pump and cgm in 2007. You can programme the pump to overcome any minor difference in the forms/manufacturer’s production. For many, Novolog seems to have a faster onset, but that might not be true for everyone, because our chemical make-ups differ from person to person. Another poster (Dr John) correctly points out that the by-product of each type of insulin production can have an effect, but if there is a problem it is more likely to be from Humalog. I’ve been on both and prefer the Novolog, but if my insurer insisted on Humalog, i could take that. If your daughter has both pump & cgm, keep an eye on her BGs, and perhaps create a journal for the short term so you can log if she has any serious issues or differences. Best of luck.
Doctors and insurance formularies will tell you they’re essentially the same and interchangeable. For most people that’s perfectly true. They are produced differently, though, and have different preservatives. Some of us actually react poorly to one. I might be biased given my personal allergy, but it seems like Humalog gets more adverse reactions than Novolog.
Humalog is made from genetically engineered e. coli bacteria, which is known to produce large amounts of histamine as a metabolic byproduct. (Concerts histadine into histamine.) The very same histamine associated with seasonal allergies and other reactions.
Conversely, Novolog is made genetically engineered yeast. It just seems to be a little cleaner and less reactive.
I much prefer Novolog!
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Thank you everyone! All of your responses have been super helpful.
This is all slightly challenging for me since my daughter has special needs, and I’m the one who has to manage most of her diabetes. I believe for most of you, you can detect subtle changes or differences in your bodies (and the impact of your dosing and the insulin you’re taking), but she’s not so terribly aware of the impact of various factors so that’s on me to figure out those things.
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Respect. Diabetes is hard enough for the person that his it. Managing it without the feelings or good communication is an incredible achievement. Great job mom.
I’m with others, I switched and found no difference. But there is some small percentage of people for whom it does matter so as a caregiver be prepared just in case. Make sure you have at least 90 days of Humalog in the fridge just in case the Novolog doesn’t work out. Check the 2026 version of your drug plan formulary for Lispro and Admelog. Until you try Novolog pay close attention to how pump sites look and feel, both size and firmness, after removing the canula or pod. When trying a new insulin watch for rubbing or scratching around the site.
Normally I suggest people take a look at the different ingredients when changing medicines just to get an idea of how different they are but since you probably don’t have any time to spare I took a look and the inactive ingredients Humalog has water and Novolog has salt, both have metacresol, used as a preservative, novolog has half as much. The rest of the ingredients are the same.
I hope the switch is trouble free for you and your daughter. In case its not, here’s Lilly’s discount program. Her doc can also do the paperwork to request a formulary exception.
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Thank you so much! That’s excellent advice. We typically have quite a bit of Humalog in reserve so having 90 days of it while she’s on Novolog should work out well. Thank you also for mentioning the ingredient differences. I hope there’s no noticeable difference in how the Novolog affects her as many people have said in their responses.
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I’ve used Humalog for most of my life, well since the NPH days (been a Type 1 for 34 years) and switched because I noticed I was having REALLY bad insulin resistance to Huamlog. To the point where when I was high it was extremely hard to get my blood sugars down it would take just about all day to get it down. It’s like my body got tired of using it after taking it for so long.
So I switched to Novolog about 3 years ago (my insurance has since stopped covering Humalog). Never had any issues out of Novolog until last year. I noticed that I was having tons of Occlusion alarms with it. I NEVER would make it through 3 days with an infusion (sometimes I’d get occlusion alarms after just a couple of hours) and come to find out my Endo thinks somehow my body started rejecting the insulin or I became allergic too it. I would develop big bumps around the infusion sites and it would clog so the insulin could no longer be delivered. So thankfully they wrote me a prior authroization to the insurance claiming that I could NO LONGER take Novolog insulin because of this and my insurance approved and started covering Humalog for me again. Needless to say I’m back to using Humalog and very rarely have an occlusion alarm anymore.
But overall the insulins are about the same to me now.