Insulin pen needles: effects of extra-thin wall needle technology on preference, confidence, and other patient ratings.

Background: Pen needles (PNs) are essential for insulin injections using pen devices. PN characteristics affect patients' injection experience.

Objective: The goal of this study was to evaluate the impact of a new extra-thin wall (XTW) PN versus usual PNs on overall patient preference, ease of injection, perceived time to complete the full dose, thumb button force to deliver the injection, and dose delivery confidence in individuals with diabetes mellitus (DM). Subjects injected insulin with the KwikPen(TM) (Eli Lilly and Company, Indianapolis, Indiana), SoloSTAR(®) (sanofi-aventis U.S. LLC, Bridgewater, New Jersey), and FlexPen(®) (Novo Nordisk A/S, Bagsvaerd, Denmark) insulin pens, and included some with impaired hand dexterity.

Methods: We first performed quantitative testing of XTW and comparable PNs with the 3 insulin pens for thumb force, flow rate, and time to deliver medication. A prospective, randomized, 2-period, open-label, crossover trial was then conducted in patients aged 35 to 80 years with type 1 or type 2 DM who injected insulin by pen for ≥2 months, with at least 1 daily dose ≥10 U. Patients who used 4- to 8-mm length PNs with 31- to 32-G diameter were randomly assigned to use their current PN or the same/similar size XTW PN at home for ~1 week and the other PN the second week. They completed several comparative 150-mm visual analog scales and direct questions at the end of period 2.

Results: XTW PNs had statistically significant better performance for each studied PN characteristic (thumb force, flow, and time to deliver medication) for all pens combined and each individual pen brand (all, P ≤ 0.05). Of 216 patients randomized to study groups (80, SoloSTAR; 77, FlexPen; 59, KwikPen), 209 completed both periods; 198 were evaluable. Baseline characteristics revealed a mean (SD) age of 60.8 (9.3) years, insulin pen use duration of 4.3 (4.1) years, and mean total daily dose of 75.1 (52.3) U (range, 10-420 U). Approximately 50% of patients were female; 81.5% were white and 14.8% were black; and 89.8% had type 2 DM. Nearly 99% used a single PN: 8 mm, 49.5%; 5 mm, 24.1%; 6 mm, 14.4%; and 4 mm, 12.0%. Patients rated the XTW PNs (mean [95% CI]) as preferable by a mean of 31.9 mm (27.2-36.6), P < 0.001; XTW PNs required less thumb force, less time to inject the dose, and were rated as providing greater confidence in full dose delivery by 28.4 mm (23.7-33.2), 21.7 mm (17.0-26.4), and 24.4 mm (19.7-29.1), respectively; all, P < 0.001. Results were similar for each of the 3 pens, those with impaired hand dexterity, and for all users of 4-mm PNs. Skin leakage and insulin dripping from the needle tip were rated as less frequent with the XTW PNs (P < 0.05). The most common adverse events were hypoglycemia in 8.3% and 6.0% of patients using XTW PNs and current PNs (P = NS), respectively; hyperglycemia occurred in 2.9% and 4.1% (P = NS). None of the adverse events was serious or considered device related.

Conclusions: XTW PNs were preferred overall, rated as requiring less time and less thumb force to inject, and providing greater confidence in completing a full dose compared with usual PNs in this group of patients with type 1 or type 2 DM. ClinicalTrials.gov identifier: NCT01852136.