Nine male patients (51.6 ± 5.4 years of age [means ± SE; range 22–69], HbA_1c 7.3 ± 0.4% [ref. <5.2%], BMI 24.3 ± 1.0 kg/m², and duration of diabetes 34.9 ± 5.1 years) were recruited from the Diabetes Day Care Unit at Danderyd University Hospital. Selection of subjects was based on the detection of a visible, palpable, and massive thickening of fat tissue with higher consistency and grade of lipohypertrophy at the site of injection and a diameter of 6–10 cm. No patient had measurable plasma C-peptide levels (ref. <0.1 nmol/l). Seven patients were treated with multiple daily injection therapy and two with continuous subcutaneous insulin infusion. Their mean daily insulin dose was 53.6 ± 4.2 units, which included a breakfast insulin dose of 5.8 ± 1.3 units. The local ethics committee of Karolinska Hospital approved the study protocol, and all subjects provided written informed consent.