Novolog vs. Humalog

Before I get to the subject of my post, I have been watching this forum for quite a while, learning what I could before switching from the Medtronic 670G to the Tandem/Dexcom 6. What an educational site! I have learned so much from the wisdom and experience of others. A special shout-out to Dennis, Joe, WearsHats, and wadawabbit. Your posts have saved me a lot time in making this transition. Thank you very much!

I just completed training for the new pump and CGM a few weeks ago. I have been using Humalog since I started pump therapy about 14 years ago. I have always changed the cartridge and inset site every 3 days as recommended. Never had a problem.

However, the training packet from Tandem states in the Overview section:
“A) Type of insulin - U100 only Novolog/NovoRapid/aspart (72 hrs.) / Humalog/lispro (48 hrs.)”

The Diabetes Educator said because I use Humalog I would need to change my cartridge and inset site every 2 days. With Novolog I could extend that to 3 days.

I don’t remember hearing that or reading that with using my previous pumps. So far with the Tandem using Humalog, I’ve been changing every 3 days like I have always done with my previous pumps. I have not encountered any problems yet. And I hope I never do as the health insurance won’t cover Novolog.

I would love to hear from Humalog users (whether they use a Tandem pump or not):
How often do you change sites?
If you go past 2 days, have you encountered any problems?
Any information you may have about Humalog that would be helpful here.

Thanks for your help. I’m still learning.


I’ve had a Tandem pump for about 10 years now and have used both insulins for 3 days with no problems. If it’s working for you that’s what matters.
Don’t forget (you probably know this but this is for people who don’t​:wink:) insurance companies may cover an insulin they say they do not, if doctor shows medical necessity. Some people are allergic to certain formulations, or simply don’t do well on a particular one - my insurance even switched to a formula that wasn’t approved for pumps (:flushed::grimacing:!) so there may be ways around that - although I doubt number of days in a pump qualifies. Just a side note.

But yes, if you’re not having problems, I say keep doing what you’re doing.

@mcpaulus I think that each formulation of insulin needs to be cleared for use in each pump. Medtronic pumps test insulin by vibrating it in a controlled temperature environment of 100F. Then the insulin is sampled for breakdown every hour. A data set is created which proves the eventual degradation of insulin is suitable, such as for 2,3,or 4 days under the test conditions.

So like all testing, a 2 day declaration from Tandem is probably extremely conservative. And that’s why some people go 4-5 days with a 300 unit reservoir, with no problems even though the documents say to change the set at the end of day 3.

If you are getting good results, I say then keep at it. I do see more scarring when I leave my sets in for 4 days versus 3 but I run the pump clean out of insulin before changing it.

Thanks for the shout out you made my day! :grinning::four_leaf_clover:

Welcome. Thanks for the shoutout. It’s really nice to hear I’ve been of help. :slight_smile:

I’ve used both Humalog and Novolog (switching over when insurance decided they got a better deal from the other company) and the switch was seamless. Never noticed a difference between the two. (Switching from Lantus to Levemir, back before I was on a pump, was a major disaster, though. My body just did not react well to Levemir and I lost 6 months of my life before I convinced my doctor and my insurance company that I needed to switch back.)

Honestly, I use a lot of insulin. My average is over 80 units a day. The pump chamber tops out at 300, and some of that goes to fill the tubing. So I just fill the thing all the way and change whenever it gets empty. It’s a little more than 3 days. Maybe 3.5. It varies a bit. But I’ve never had a problem with either type of insulin.

There is no medical reason to change sets that often. It is possible to develop scar tissue but if that is the case, why are they all now developing sets that last a week to 10 days. It is lawyers and sales people selling sets that say change that often. My Endo always asks me how often I change for the presecription but has never said anything about changing every 6 days when the insulin runs out. I am not a doctor but I have used a pump for 30 years and have always just changed when the 3ml of insulin runs out which is usually 5 to 6 days. My time in range is 90% and I have a 5.2 A1C.

Hi @808IUFan . I used to leave mine in for a week with no problems, but my doctor told me I should change every 3 days - I think it was to avoid scar tissue but I’m not sure. I wasn’t aware they were making sets for me extended use - do you have any links to the info? I might like to check it out. Thanks much.

I do not have links because they are still in developement or waiting on FDA approval. I also am on everyone’s list to take surveys for medical device makers where they ask do you like this or do you like that. Some of the things being explored are leaving infusion sets in so long, they have had to developed a way to refil the insulin using the same set. They attach the vial to the pump. In Medtronic videos however, they are saying changing less often helps to lower scar tissue because you are not using as many sites. It has been a sales tool for infusion sets all along.

Thanks. I’ll keep my ears open for future developments!

I use humalog, averaging about 28 units a day. I always use my 180 unit reservoir for 4-5 days and I have rarely if ever had a problem. What I do notice is that the insulin seems a little more “powerful” on the first day. So if I put in a new reservoir at evening I will be a little extra careful because I find it has a little more kick to it the first 24 hours.

The fact is that if you change it every three days you are using more insertion sites on a regular basis versus if you change it less often, you may have more scarring (not something I have noticed), but you are also giving more time to unused areas to heal up by leaving it in longer. Don’t think they have any scientific proof of this.

I have worked in sales for a long time and it is hard not to just crunch this down to pure financial numbers for the companies who sell this stuff. Ask doctor if they are aware of any scientific research about using it 3 versus 4-5 days. Most likely the doctor is only passing down what these companies have said to do.

This is just my opinion. Everyone should do what they are comfortable with I feel.