Ultra-fast Insulins Curb Mealtime Spikes

Anne L. Peters, MD


October 27, 2017

Today I am going to talk about two ultra-fast–acting insulins. The first is the newly approved faster-acting insulin aspart, called Fiasp®. The other is an older, inhaled insulin, Afrezza®.

First, let me explain why we need ultra-fast–acting insulins. If any of your patients with type 1 diabetes are on a continuous glucose sensor, they will be somewhat disturbed when they give their insulin before a meal and still see a fairly high postprandial glucose excursion. This happens largely because the insulin they have injected takes 15 to 30 minutes to begin to bring down that postprandial glucose level. The insulin has not had a chance to start working, and they are ingesting carbohydrates and seeing these postprandial spikes.

To address that, we tell patients to take insulin 15 to 30 minutes before the meal. But that is highly inconvenient for many patients, and often they do not do that. Thus, there clearly is a need for faster-acting insulin.

The faster-acting insulin aspart Fiasp has been available in Canada and other countries for a short while. This insulin works faster than the usual insulin aspart, much closer to the time it is injected. A person can actually give it right before the meal and it will start acting as the food is being absorbed. The effect does not last quite as long as the usual aspart insulin, but it does have a fairly long half-life after it has been injected.

What is most important is that it acts so much faster initially. Patients have been able to inject it closer to the beginning of a meal and have a better postprandial response.

The downside is that because it acts fast, if the patient injects it and then gets distracted and does not eat right away, the blood sugar can go too low. There has not been a lot of difficulty with this in general, because patients tend to give it just when they are sitting down to eat.

It can be given as an injection and also, although not yet approved, it can be used in an insulin pump. This makes sense because for the bolus doses of insulin in a pump, you want an insulin that acts quickly.

Afrezza: Fast On, Fast Off

The other insulin is Afrezza, the second inhaled insulin on the market. Although Afrezza has been available for a while, the label was changed recently to include the point that it is both faster on and faster off.

Afrezza comes in small 4-unit, 8-unit, and 12-unit cartridges. Before a meal, the patient puffs on a device that looks like a whistle. It is very fast in terms of its initial absorption, and then it comes down and goes away. It is eliminated quite quickly.

I find that patients also benefit from Afrezza when it's given as a correction dose if the patient’s blood sugar is very high and not coming down; giving a puff of Afrezza helps the sugar come down without going too low.

In addition, I have been using it more recently as a premeal insulin. Patients on continuous glucose monitors may notice that their insulin wears off too soon and they need a second postprandial dose of Afrezza to maintain level blood sugars. I believe that Afrezza also is useful for patients who want that quicker reduction in their blood sugar levels, but with Afrezza, patients must be forewarned that it could actually wear off too quickly and they may need that touch-up dose, that second dose after a meal to fully maintain euglycemia.

I believe that both of these insulins are quite useful, particularly for our patients who wear continuous glucose monitors and see the need for a faster-acting insulin. These insulins act faster so they can be taken just before the meal. In the case of Afrezza, the patient may need a touch-up dose after the meal to maintain normal blood glucose levels. But both of these are options now for our patients who are striving for improved glycemic control.


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