Does Size Matter? Thoughts About Insulin Pen Needles

Abstract

T he improvements of needles for insulin delivery in general, and pen needles (PNs) in particular, have been an amazing evolution. It is difficult to imagine “patient comfort” was an important criterion for the use of the original insulin pens since the 29-gauge (G)×12.7-mm PN used was similar to the needles with syringes. The original promise of the insulin pen was more about the convenience and accuracy of the pen (compared with a syringe) rather than any advantage of the needle used. It is interesting that in the United States insulin pen use continues to lag behind that in the rest of the world. In 2009, vial and syringe use was above 70% in the United States, whereas in countries such as Australia, China, France, Germany, Japan, The Netherlands, Poland, Spain, Sweden, Turkey, and the United Kingdom this older form of insulin delivery made up less than 10% of use.¹

But insulin pen use is increasing in the United States, and this is occurring with improvements in the PNs. One recent American study showed no differences in glycemic control but improved patient ratings comparing 32G×4-mm with 31G×5-mm and 31G×8-mm PNs.² These data included 163 subjects in the final analysis using fructosamine as the glycemic metric in this 3-week crossover study. It is important that the mean body mass index in this study was 31.0 kg/m². In this issue of Diabetes Technology and Therapeutics, Miwa et al.³ showed similar results with a Japanese population with a mean BMI of 23.2 kg/m². Glycated albumin was the metric for glucose control, and the population was smaller; 41 patients were studied. Still, there were no differences for glucose control in this crossover trial comparing 32G×4-mm versus 32G×6-mm PNs.³ Safety was also similar between the two PNs, as were the measures of quality of life.

The conclusion is that these smaller PNs are more desirable to the majority of patients, and the hope is that this would improve adherence and perhaps even ease some of the fear of starting insulin for many. However, there are two concerns that need to be addressed.

First, how would the results of both the American and Japanese studies differ if needle use was more than once? Although the recommendations from the PN manufacturers are to use the needle one time only, it is not realistic to believe that outside a clinical trial (where supplies are provided) this is routine practice. It is difficult to know how often patients actually change their PNs, but my observation is that few change for each injection, and in fact I suspect most don't even change each day. Would glycemic control, pain, and other measures from the subject preference questionnaire be different if this was a “real-life” study with each PN used multiple times? Ideally, these studies should be repeated with PNs used multiple times.

Second, we are receiving more barriers from some payers for using insulin pens because of the increased cost. In the United States, insulin in a pen costs about 30% more than the same insulin in a vial. Although no one can quote the cost for the payers in other countries, it is safe to say that the cost of the pen insulin (cartridge or disposable) is cheaper in countries with the most insulin pen use, such as China, Japan, Poland, and Spain.¹ Often forgotten in the cost of the pen insulin is the added cost of the PNs. This is not a trivial point as we move forward in the era of Accountable Care Organizations and the need for value with all of our medications and devices. What are clearly needed are cost outcome studies based on actual prices comparing a vial and syringe versus an insulin pen with PNs. The difficulty, of course, is putting a price tag on quality of life. Unfortunately, for some payers this has little value. This to me is the most disappointing aspect of our enthusiasm for “evidenced-based medicine.”

While I have no doubt most patients prefer the smaller needles, which result in no change in glycemic control when used one time, I am hopeful these other issues can be addressed in the near future.

References

Perfetti

. Reusable, disposable insulin pens for the treatment of diabetes: understanding the global differences in user preference, an evaluation of inpatient insulin pen use. Diabetes Technol Ther, 2010; 12,Suppl 1:S-79–S-85.

Hirsch

, Gibney

, Albanese

, Qu

, Kassler-Taub

, Klaff

, Bailey

. Comparative glycemic control, safety, and patient ratings for a new 4 mm×32G insulin pen needle in adults with diabetes. Curr Med Res Opin, 2010; 26:1531–1541.

Miwa

, Itoh

, Kobayashi

, Tanabe

, Shikuma

, Takahashi

, Odawara

. Comparison of the effects of a new 32-gauge×4-mm pen needle and a 32-gauge×6-mm pen needle on glycemic control, safety, and patient ratings in Japanese adults with diabetes. Diabetes Technol Ther, 2012; 14:1084–1090.