Background: To reduce the risk for long-term complications in diabetes mellitus, glycaemic control is essential. However, reluctance and suboptimal compliance with multiple daily injection regimens complicates achieving good glycaemic control in diabetic patients. This study was designed to elucidate a novel route of administration; painless transdermal microneedle patches. Methods: Diabetes was induced by an intravenous injection of streptozotocin (50 mg/kg BW, Sigma-Aldrich, USA). After Inactin-anaesthesia, surgery and a 45 minutes recovery period, plasma insulin and glucose were recorded while lispro insulin (2 ml/h, 100 IE/ml, Eli Lilly Sweden AB, Sweden) was administered for 180 minutes, either as a subcutaneous (sc) or transdermal (td) infusion. Hereafter, plasma insulin and glucose were recorded for another 60 minutes. Results: At baseline, all animals displayed a pronounced hyperglycaemia (19.1 + -0.5 mM). Lispro insulin resulted in reduced plasma glucose, whether given sc (from 18.4 ± 2.6 to 9.1 ± 3.8 mM) or td(from 18.6 ± 1.0 to 10.6 ± 1.8 mM). In the td animals, plasma insulin was increased in all later measurements (7.2 ± 2.2, 8.1 ± 3.4, and 8.7 ± 2.0 mIE/ml), as compared to the first measurement (2.6 ± 1.3). In the sc animals, plasma insulin was elevated during the last measurement (to 15.4 ± 3.5 mIE/ml from 2.1 ± 1.8). Conclusion: This study presents a novel possibility of insulin delivery that is controllable and requires minimal training. The novel, transdermal infusion also showed a significant effect on plasma glucose before such an effect was obtained with subcutaneous infusion, possibly due to the larger infusion area. This treatment strategy could improve compliance, and thus be beneficial for patients' glycaemic control.