A study led by Per G. Clauson, MD, in Stockholm, Sweden recently determined that the absorption of rapid-action insulin is slow in both obese and non-obese patients with type 2 diabetes when compared with type I patients.
As reported in the July 1995 issue of Diabetes Care, participants in the study were divided into obese and non-obese groups. All were given a breakfast of cereal, a ham and cheese sandwich with margarine, orange juice, and decaffeinated coffee or tea. They then received four simultaneous injections of radiolabeled rapid-acting insulin-three in different parts of the abdomen and one in the thigh. The choice of insulin injection was of little importance in the obese group since the absorption differences are small in heavier patients. All the participants were asked to lie on their backs for the duration of the testing, except when sitting up to eat the standardized lunch. The residual radioac-tivities of the radiolabeled insulin were monitored every minute.
It was found that the absorption rates from the various injection sites in the non-obese group varied significantly, the highest rates being in the upper-abdominal area and the lowest rates from the thigh. In the obese group, the differences were small. It appeared that the depth of fat layers on different injection sites was not a major factor in absorption (but some other studies have shown otherwise).
Obesity apparently is not a determiner of insulin absorption-a more significant factor is type 2 diabetes, which causes insulin to be absorbed between 15% and 45% slower than type I diabetes.
Time to 50% elimination of rapid-acting insulin (5 U) after subcutaneous injection in thigh and abdomen in 10 nonobese type 2 and 10 obese type 2 patients:
Above navel}242 (minutes)}196 (minutes)
Sides of navel}274}250