title: Impact of a modified needle tip geometry on penetration force as well as acceptability, preference, and perceived pain in subjects with diabetes.
abstract: BACKGROUND
  Multiple factors impact subcutaneous insulin injection pain. Injection devices [e.g., syringe or pen needle (PN)] affect pain due to needle length, diameter, needle polishing and lubrication, and needle tip geometry.
  
  
  METHODS
  We evaluated a modified 5-bevel PN tip in 32 G × 4 mm 31 G × 5 mm and 8 mm PNs vs the equivalent marketed 3-bevel PNs in laboratory penetration force testing, as well as in insulin-taking subjects for overall acceptability, comparative pain, and preference. The clinical tests were done in three ways: paired insertions with the subjects blinded to PN tip geometry, after brief at-home use of 5-bevel PNs, and again with subjects informed about each needle's tip geometry in paired insertions.
  
  
  RESULTS
  Average penetration force in a skin substitute was 23% lower with the 5-bevel PNs vs similar 3-bevel PNs (p ≤ 0.01). In blinded testing and after at-home use, patients rated the 5-bevel needle as acceptable. After shortterm home use, patients rated the 5-bevel PN less painful and preferable to their usual PN (both p < 0.01). In paired, informed testing, the 5-bevel PN was less painful and preferred to subjects' currently used needles (p ≤ 0.01) and to other marketed PNs (p < 0.01).
  
  
  CONCLUSIONS
  Needle tip geometry affects penetration force. When blinded, patients did not distinguish differences in PN tip geometry with fine-gauge PN insertions. A 5-bevel needle tip is perceived as less painful and is preferred by subjects following home use for usual injections. Similar results occurred when patients were informed that they were using a needle with a modified tip.
authors.affiliation: BD (Becton, Dickinson and Company), Franklin Lakes, New Jersey, USA. laurence_hirsch@bd.com
authors.forename: Laurence
authors.initials: L
authors.lastname: Hirsch
authors.forename: Michael
authors.initials: M
authors.lastname: Gibney
authors.forename: Julie
authors.initials: J
authors.lastname: Berube
authors.forename: John
authors.initials: J
authors.lastname: Manocchio
mesh_terms: D000328:Adult; D000368:Aged; D003920:Diabetes Mellitus / Q000188:drug therapy*; D016503:Drug Delivery Systems / Q000009:adverse effects / Q000295:instrumentation*; D004867:Equipment Design; D005260:Female; D006801:Humans; D007004:Hypoglycemic Agents / Q000008:administration & dosage*; D007279:Injections, Subcutaneous; D007328:Insulin / Q000008:administration & dosage*; D008297:Male; D008875:Middle Aged; D009339:Needles; D009515:New Jersey; D010146:Pain / Q000209:etiology* / Q000503:physiopathology / Q000517:prevention & control / Q000523:psychology; D010147:Pain Measurement; D058748:Pain Perception; D017288:Pain Threshold; D057240:Patient Preference; D017060:Patient Satisfaction; D011446:Prospective Studies; D011795:Surveys and Questionnaires; D055815:Young Adult
chemical_list: D007004:Hypoglycemic Agents; D007328:Insulin