title: Minimally invasive insulin delivery in subjects with type 1 diabetes using hollow microneedles.
abstract: BACKGROUND
  Microneedles have previously been used to deliver insulin to animal models, but not in human subjects. This study tested the hypothesis that hollow microneedles can deliver insulin to modulate blood glucose levels in subjects with type 1 diabetes in a minimally invasive manner.
  
  
  METHODS
  This study was carried out in two adults with type 1 diabetes and evaluated bolus delivery of lispro insulin using a hollow microneedle compared to a catheter infusion set (9 mm). The study first determined the minimum insulin delivery depth by administering insulin from microneedles inserted 1, 3.5, and 5 mm into the skin of fasting subjects and then assessed the efficacy of insulin delivery from microneedles inserted 1 mm into the skin to reduce postprandial glucose levels. Blood samples were periodically assayed for plasma free insulin and plasma glucose levels for up to 3.5 h.
  
  
  RESULTS
  The first phase of the study indicated that microneedles inserted at the shallowest depth of 1 mm within the skin led to rapid insulin absorption and reduction in glucose levels. Bolus insulin delivery followed by consumption of a standardized meal in the second phase revealed that microneedles were effective in reducing postprandial glucose levels. Subjects reported no pain from microneedle treatments, and there were no adverse events.
  
  
  CONCLUSIONS
  This study provides the first proof of concept that hollow microneedles can effectively deliver bolus insulin to type 1 diabetes subjects in a minimally invasive manner.
authors.affiliation: School of Chemical & Biomolecular Engineering, Georgia Institute of Technology, Atlanta, Georgia 30332-0100, USA.
authors.forename: Jyoti
authors.initials: J
authors.lastname: Gupta
authors.forename: Eric I
authors.initials: EI
authors.lastname: Felner
authors.forename: Mark R
authors.initials: MR
authors.lastname: Prausnitz
mesh_terms: D000328:Adult; D000818:Animals; D001786:Blood Glucose / Q000378:metabolism; D003922:Diabetes Mellitus, Type 1 / Q000097:blood / Q000188:drug therapy*; D005260:Female; D006442:Glycated Hemoglobin / Q000378:metabolism; D006801:Humans; D007279:Injections, Subcutaneous / Q000009:adverse effects / Q000295:instrumentation / Q000379:methods*; D007328:Insulin / Q000008:administration & dosage* / Q000627:therapeutic use; D007332:Insulin Infusion Systems; D008297:Male; D008832:Microchemistry / Q000295:instrumentation / Q000379:methods*; D008904:Miniaturization; D010146:Pain / Q000209:etiology; D019518:Postprandial Period
chemical_list: D001786:Blood Glucose; D006442:Glycated Hemoglobin; D007328:Insulin