Hyperinsulinemic-Euglycemic Clamps Using Insulin Detemir and Insulin Glargine in Healthy Cats
Insulin detemir (Levemir®) and insulin glargine (Lantus®) are synthetic long-acting insulins used in human medicine. Reports of the use of Lantus in cats are rare, and the use of Levemir in cats has not, to our knowledge, been reported. In people, Lantus is longer acting and relatively peakless, while Levemir has significantly less within-subject variability. Levemir is also associated with less undesired weight gain and decreased frequency of hypoglycemic events. Because Levemir may prove useful in the treatment of feline diabetes mellitus, we performed hyperinsulinemic-euglycemic clamps in cats, comparing regular insulin (Humulin® R), Lantus and Levemir.
Five young, healthy, purpose-bred cats received subcutaneous injections of 0.5 U/Kg of Humulin R, Lantus and Levemir separately, on 3 different days, at least 1 week apart. Following each insulin injection, the blood glucose concentration, measured every 5 minutes, was maintained at baseline by a constant rate infusion of glucose, and the glucose infusion rate (GIR) was recorded. The duration of action was defined as the time from insulin injection until GIR stabilized at zero. The peak insulin action was defined as the peak GIR. The onset was defined as the time from insulin injection to initial increase in GIR. No adverse reactions were observed with any of the insulin products. The median duration of action of Humulin R was 305 minutes (range: 140-370 minutes). Lantus had a median duration of action of 470 minutes (range: 295-950 minutes). Levemir had a median duration if action of 800 minutes (range 525-915). In 3 cats, the duration of Levemir exceeded the duration of Lantus by 205-505 minutes. In the other 2 cats the duration of action of Lantus was slightly greater than that of Levemir (25 and 35 minutes longer). When compared using the Kruskal-Wallis test the durations of action of the 3 insulins were significantly different (P = 0.012). When compared using the Mann-Whitney U test, the duration of Levemir was significantly greater than that of Humulin R (P = 0.008), but there was no significant difference between Lantus and Humilin R (P = 0.095) or between Lantus and Levemir (P = 0.31). The peak effects of Lantus occurred between 120 and 585 minutes. The peak effects of Levemir were less variable among the 5 cats, occurring between 370 and 575 minutes. The median time of onset of Lantus was 80 minutes (range: 50-110 minutes), compared with 135 minutes (range: 80-165 minutes) for Levemir (P = 0.11).
In young healthy cats, Lantus may have a more rapid onset than Levemir, but the peak effect of Levemir is somewhat more predictable. The duration of Levemir may be greater in some cats. Investigation of the clinical use of Levemir in diabetic cats is warranted.