Different between basal and long acting insulin?

I was wondering if anyone knew if basal insulin acts differently cellularly or effects the body differently than long term insulin like lantus or levemir does. I know on basal insulin from a pump, you’re constantly getting a supply of “fast” acting insulin steadily throughout the day. But with long acting insulin you only take one shoot and i’m not sure how that’s broken down or abosrbed throughout the day.

my understanding is that lantus crystallizes in your subcutaneous lipid tissue and acts slowly over a 24 hour period, or at least that it’s supposed to. i don’t know more specifics but there are people who have bioE/biochem backgrounds who post here who might be able to say more.

Lantus stays aqueous (liquid) in acidic conditions, once it hits your body where the PH is realtively neutral it drops out of solution and forms crystals, throughout the day very small amounts of the crystal disolve into the SC tissue and release into the bloodstream, it has been designed so that it takes around 24 hours to completely disolve. Levemir does not crystalize, but has some effect where the Levemir molecules are attracted to fatty tisue and very slowly several insulin molecules break away and enter the bloodstream, I am not very clear on how it accomplishes this. Rapid insulin is chemically modefied to be less stable of a molecule than regular insulin and is able to release the actual insulin piece of the molecule into the bloodstream much quicker.

The term basal in diabetes care refers to the absolute minimum amount of insulin required to maintain level Bg levels through out the course of a day without adding food. On a cellular level the long acting insulins work the same as “fast acting” and are considered basal insulins as well. Unlike pumping, in which small doses of fast acting are administered through out the day, a long acting (basal) insulin such as Lantus or Levermir is used.

For those of us these insulins we are basically injecting a days worth of “basal” insulin into the SC tissue where as posted above they are stored and held inert, to be released slowly over the day. Levemir’s action is actually based on it’s attraction to albumin (a protein) in our bodies where it becomes bonded to upon injection holding the insulin inert. Over the course of its action it becomes active by slowly disassociating itself from the albumin ideally over 24 hours.

A basal insulin performs the function of providing blood sugar regulation during fasting. A basal insulin function can be provided by any number of insulin’s with different times of action. You can inject a long acting insulin like Levemir or Lantus once or twice a day, you could inject an intermediate, like NPH two or three times a day. Or you could inject a rapid insulin in little squirts all throughout the day, which is exactly how a pump implements a basal insulin.

The long acting insulin’s operate in different ways. NPH and Levemir both are modified by attaching the insulin molecule to a protein molecule (here is an explanation). Over time, the bond is broken and the insulin acts on your body. Lantus is mixed with an acidic solution which when injected into your body and suddenly shifted to a neutral PH causes the formation if little crystals. These crystals dissolve over time, releasing the insulin (here is an explanation and a Video).

In the case of older insulins R and NPH, the insulin molecule is exactly identical to human insulin. In the case of newer insulins, the molecule is slightly modified. It still acts like insulin, performing the same function, but it has a modified profile of action in the body and has slightly different chemical properties that mean it attaches to other things differently (like the albumin in Levemir).

I am glad that I am not the only person here who gets better control with MDI than a pump! Mine problem wasn’t having something attached to me but problems with sites going bad so fast, even with proper rotating. If I got 48 hours out of a site, that was a miracle. I was seeing 200s almost every day on a pump.

Long acting insulins bind to molecules in your body, like proteins. As your body breaks down the host molecule, the insulin is free to bind to insulin receptors. The length of the non receptor binding, breakdown and subsequent release is the length of the action of the insulin. I am sure there are other methods for doing this, but this is how I understand the action of levemir. There is no difference between the actual insulin molecules that are eventually bound to receptors, just how they get to the receptor.

The injection into subCU tissue is for a couple reasons. A very important one that has nothing to do with the action of insulin is mitigating infection. Its a lot easier for your body to counter act pathogens in isolated subcutaneous tissue than if they were diffusing into tissue all over your body. I think its also easier for it to bind to whatever transport molecule from subcutaneous tissue as well, but thats just a guess.