Novel microneedle patches for active insulin delivery are efficient in maintaining glycaemic control: An initial comparison with subcutaneous administration

Purpose. Good glycaemic control is essential to minimize the risk for diabetes-induced complications. Also, compliance is likely to be higher if the procedure is simple and painless. This study was designed to validate painless intradermal delivery via a patch-like microneedle array. Materials and Methods. Diabetes was induced by an intravenous injection of streptozotocin (50 mg/kg bw) in adult male Sprague Dawley rats. Plasma insulin and blood glucose were measured before, during and after subcutaneous or intradermal (microneedles) infusion of insulin (0.2 IU/h) under Inactin-anaesthesia. Results. Before insulin administration, all animals displayed a pronounced hyperglycaemia (19 +/- 1 mM; 359 mg/dl). Administration of insulin resulted in a reduced plasma glucose independently of administration route (subcutaneous 7.5 +/- 4.2, n=9, and intradermal 11 +/- 1.8, n=9 after 240 min), but with less errors of the mean in the intradermal group. In the intradermal group, plasma insulin was increased in all latter measurements (72 +/- 22, 81 +/- 34, and 87 +/- 20 mu IU/ml), as compared to the first measurement (26 +/- 13). In the subcutaneous group, plasma insulin was elevated during the last measurement (to 154 +/- 3.5 mu IU/ml from 21 +/- 18). Conclusion. This study presents a novel possibility of insulin delivery that is controllable and requires minimal training. This treatment strategy could improve compliance, and thus be beneficial for patients' glycaemic control.