This study determined the influence of needle length for insulin administration on metabolic control and patient preference in obese patients with diabetes mellitus.
In this multicenter, open-label crossover study, insulin pen needles of two different lengths (5 mm and 8 mm) were compared. A total of 130 insulin-treated type 1 and type 2 diabetes patients with a body mass index ≥30 kg/m2 were randomized, and 126 patients completed the study. Patients started using the 5-mm needle for 3 months, after which they switched to injecting insulin with the 8-mm needle for another 3 months, or vice versa. Hemoglobin A1c (A1C), fructosamine, and 1,5-anhydroglucitol were measured, and self-reported side effects and patient preference were recorded.
No within-group changes were observed with respect to A1C, serum fructosamine, 1,5-anhydroglucitol, hypoglycemic events, bruising, and pain. When data of all 126 subjects were pooled, there was a small, but significant, difference between needle lengths (5-mm, A1C 7.47 ± 0.9%; 8-mm, 7.59 ± 1.0%; P = 0.02). Patients reported less bleeding with the 5-mm needle (P = 0.04) and less insulin leakage from the skin with the 8-mm needle (P = 0.01). There were no significant differences in patient preference, with 46% of the patients preferring the 5-mm needle, 41% the 8-mm needle, and 13% not preferring a particular needle length.
A 5-mm needle is similar to an 8-mm needle in obese patients with diabetes with respect to metabolic control, injection-related complaints, or patient preference and can be used safely.