5mm needles may be as good as 8mm for obese patients with type 1 diabetes or type 2 on insulin

Picture of a syringe

Clinical question:

In obese people (BMI ≥30 kg/m2) with diabetes who inject insulin, are 5mm needles, as compared to 8mm, effective at maintaining glycaemic control and acceptable to patients?


Randomised crossover trial with six months duration, N=130.    Glycaemic control was measured by HbA1c, fructosamine and 1,5-anhydroglucitol.  Patient preferences were measured with a visual analog pain scale.

Bottom line:

The researchers reported that 5mm needles had a slightly lower HbA1c than 8mm needles.  In all other outcomes, they found that the two needle types performed similarly.

Appraisal hints:

Users of this research are advised to consider:

  • How randomisation and treatment allocation were carried out.  Although this is not reported in detail, potential bias in this respect may be limited by the use of a crossover design, since both groups of patients used both needle types.
  • Whether the trial was sufficiently powered to establish clinically important non-inferiority between the two needle types for the key outcome of HbA1c.
  • Whether using each needle type for three months was long enough for HbA1c changes to be detectable.  Also, was six months follow-up long enough overall?
  • The validity of fructosamine and 1,5-anhydroglucitol as indicators of glycaemic control in the preceding 2-3 weeks.
  • Potential bias from lack of blinding of patients and carers.
  • The lack of reporting of many of the data analyses described in the methods section.


The full text of this paper is available from PubMed Central at the link below.

Kreugel G, Keers JC, Kerstens MN, Wolffenbuttel BH.  Randomized trial on the influence of the length of two insulin pen needles on glycemic control and patient preference in obese patients with diabetes. Diabetes Technol Ther. 2011 Jul;13(7):737-41. Epub 2011 Apr 10.

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I am an information scientist with an interest in making knowledge from systematic research more accessible to people who need it. This means you. I've been attempting this in the area of Evidence-Based Health Care since 1995. So far the results have been mixed. For some reason we expected busy clinicians to search databases and appraise papers instead of seeing patients. We also expected publishers to make the research freely available to the people who paid for it.. Ha! Hence The National Elf service.

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