Dr. Matthew Stephen is one my endocrine practice partners. Matt has lived well with type 1 diabetes for 33 years. He has used Fiasp and wrote this summary of his thoughts.
Not surprisingly, the Fiasp® FlexTouch pen looks and feels much like the Tresiba® FlexTouch.
In my limited experience so far with Fiasp, I have appreciated its rapid absorption and action. Pre-meal dosing should be done with caution especially if pre-meal glucose is low or low-normal as it is absorbed and acts noticeably more rapid than other bolus insulins.
I am not in the habit of eating a lot of simple carbohydrate meals or snacks; however, I did find it helpful in staying ahead of glucose rises with both cereal and donut intake.
Further, I found that using it in conjunction with a continuous meter device I was able to wait until there was a faint rising trend (reverse "waiting for the bend") before giving my meal time injection and still limit glucose excursion and peak.
With more experience and practice, I definitely can see potential benefits of Fiasp including flexibility for meal time dosing/time, prompter correction of high glucoses, and improved management of more complex meals.
Hopefully, Fiasp will get pediatric indication and greater insurance coverages very soon.