Impaired Absorption of Insulin Aspart From Lipohypertrophic Injection Sites

L ipohypertrophy is a common side ef-fect of subcutaneous insulin therapy,occurring in up to 50 % of patients with type 1 diabetes (1–3). It is generally held that absorption of insulin from such palpably abnormal sites is erratic, al-though the consequence thereof on glu-cose control has been considered controversial (1,4,5). Notably, a recent study using the continuous glucose mon-itoring system to monitor swings of blood glucose documented a significant correla-tion between the mean of daily differences of glucose and the severity of injection site lipohypertrophy (6). Few studies have in-vestigated insulin uptake from lipohyper-trophic tissue. Absorption of isophane (NPH) insulin, as determined by plasma free insulin, was found to be markedly defective at abnormal injection sites (7), and absorption of regular insulin (Ac-trapid) was delayed as determined by the clearance of 125I-insulin (8). It was con-cluded from these studies that the differ-ences were of sufficient magnitude to be of clinical importance. Currently, both of these insulin preparations give way to in-sulin analogs. Therefore, the present study was conducted to investigate whether the absorption of a single subcu-taneous dose of insulin aspart is impaired when administered to lipohypertrophic tissue in patients with type 1 diabetes.