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[IP] Only Small Differences Between Insulin Lispro and Aspart



Item #4
Only Small Differences Between Insulin Lispro and Aspart
www.diabetesincontrol.com/issue54/item4F.htm

Two rapid-acting insulin analogs, lispro and aspart, were compared in this 
study
after subcutaneous injection in patients with type 1 diabetes.

Fourteen patients with type 1 diabetes were recruited for the study. Only 
two
patients had measurable C-peptide levels.  All patients were on
multiple-injection therapy with a breakfast insulin dose of 11.1 1 0.7 U 
(range
614) and no intermediate-acting insulin in the morning.

The study was designed as a single blind randomized crossover study. On the
first day, seven patients were randomized to insulin lispro (Humalog, U-100; 
Eli
Lilly, Indianapolis, IN), and the other seven were randomized to insulin 
aspart
(NovoRapid, U-100; Novo-Nordisk, Bagsveard, Denmark). On the second study 
day
(521 days later), the patients received the alternative insulin analog. The
patients continued their usual insulin treatment between the study days.

The impression from previous studies is that insulin aspart gives a somewhat
broader peak than lispro. We found a significantly more rapid lowering of 
the
free insulin concentration to 50% of the peak concentration with lispro. The
plasma profile of free insulin obtained is dependent on the rate of 
absorption
of insulin from subcutaneous tissue and the elimination of insulin from the
circulation.

Because the metabolic clearance of insulin analogs is predominately receptor
mediated and because lispro and aspart have about the same affinity for the
insulin receptor, it seems probable that they will have about the same 
clearance
rate and that the lowering of free insulin after the peak is mainly due to 
the
rate of absorption.

>From the clinical point of view, the most important observation is that 
insulin
analogs are absorbed much faster than human insulin after subcutaneous
injection, with higher insulin peaks and shorter duration of action. Because
high postprandial glucose and lipid levels have been emphasized as risk 
factors,
especially in type 2 diabetes, this may be of importance. In this respect, 
the
relatively rapid rise of free insulin levels after injection of insulin 
lispro
might be an advantage.

The slightly slower decrease of free insulin concentrations after the 
insulin
peak of insulin aspart might influence the need for daytime basal insulin 
and
the need for a snack between the main meals of certain patients.

We previously found no difference in IGFBP-1 concentrations when using human
regular insulin or insulin lispro, and in this study there was no difference
between insulin aspart and lispro.

The main finding of our study is that the free insulin profiles of aspart 
and
lispro resemble each other, but insulin lispro shows a more rapid uptake,
reaches the maximum peak concentration earlier, and shows a more rapid 
decline
than insulin aspart. We believe this finding may be of clinical importance.
Diabetes Care 24:1120-1121, 2001


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