Insulin Pens: Improving Adherence and Reducing Costs

The advantages offered by insulin pens may help improve patient adherence.

Currently 8.3% of the United States adult population, or 25.8 million people, have diabetes. Of these cases, more than 90% are cases of type 2 diabetes mellitus (T2DM) and at least 1 million are estimated to be cases of type 1 diabetes mellitus (T1DM). Although a variety of oral medications are available for patients with diabetes, insulins remain an important component of treatment.^1,2

Insulins are the standard therapy in patients with T1DM and are ultimately used in patients with T2DM who do not respond adequately to other treatment modalities. Although in some settings insulins may be administered intravenously (eg, with an insulin pump), the vast majority of insulin administrations are subcutaneous injections.^1,2

Available Forms and Administration

In the United States, 2 types of insulins are available: recombinant human insulins and insulin analogs. Recombinant human insulin is available from 2 manufacturers (Humulin by Eli Lilly and Novolin by Novo Nordisk); each of these is available in a regular form and in a longer-acting neutral protamine hagedorn (NPH) form. Unlike recombinant human insulins, insulin analogs are structurally modified forms of insulin that are designed to either lower blood sugar rapidly or maintain low blood sugar levels over time. These insulin analogs may be classified as rapid-acting and long-acting insulins. Rapid-acting insulins include insulin lispro, insulin aspart, and insulin glulisine, and long-acting insulins include insulin glargine and insulin detemir. Premixed formulations of insulin are also available.^1,2

Regardless of the differences between insulin formulations, all conventional types of insulin can be administered subcutaneously. Subcutaneous injections can be given in one of 2 ways^1,2:

• Disposable plastic syringes: syringes are available in 1-, 0.5-, and 0.3-mL sizes. Because most patients with diabetes use less than 30 units of insulin per injection, the smallest syringe size is most often used. Medication is carefully drawn out of an insulin vial and into a syringe. Tiny gradation markers in the syringe aid in measuring the insulin dose. Typically, insulin vials contain 10 mL of insulin at a concentration of 100 units/mL.
• Insulin pens: pens may be prefilled and disposable, or refillable (with insulin cartridges), although most pens are disposable. In both cases, each pen contains 3 mL of insulin. A very short, very thin needle is attached to the pen before a subcutaneous injection is administered.

Insulin Pens Vs Insulin Vials

Insulin pens have several advantages for patients with diabetes. First, insulin pens eliminate the need to carry and transport vials and syringes, improving convenience and adherence. In addition, patients with T2DM—particularly advanced T2DM— may have vision problems or dexterity problems, making insulin measurement using a plastic syringe very difficult. The benefits of pens on improving the acceptability of insulin therapy and adherence with insulin therapy have been demonstrated in clinical studies^1,2:

In an observational study of 74 patients with T1DM and T2DM over 6 months, investigators interviewed patients using a vial/syringe administration system and patients using an insulin pen. Most (95.2%) patients using insulin pens rated pens as easy to use compared with fewer than half (46.7%) of patients using a conventional vial/syringe technique, a significant difference (P <.001). Patients using pens were more than twice as likely to be able to read the dosing scale easily than patients using a conventional vial/syringe technique (61.9% compared with 26.7%; P = .037).³

In a real-world outcomes study, patients with T2DM who switched from a vial to a disposable pen needle had significantly greater treatment persistence after 1 year of treatment (65.3% 1-year persistence with an insulin pen compared with 49.8% with a traditional vial/syringe; P <.0001). In addition, patients who switched had a significantly higher medication possession ratio, an indicator of greater adherence among pen users (79% compared with 76%; P = .0173).⁴

Second, insulin pen needles can be as thin a 31 gauge and have a short length of 5, 6, or 8 mm. Short, thin needles help reduce the pain associated with injections. Evidence supports reduced pain and improved patient preference with thinner, shorter needles. In a 74-patient observational study, investigators found that a significantly greater proportion of pen users than needle/syringe users reported no injection-related pain (76.2% using insulin pens were free of injection-related pain compared with 26.7% of patients using traditional vial/syringe injections; P = .003).³

In 6-month preference study of Canadian patients with diabetes, 66 obese patients received subcutaneous insulin injections with an 8-mm needle for the first 3 months of the study and a 5-mm needle for the last 3 months of the study. Having used both syringe lengths, by the end of 6 months, 41.8% of patients were more satisfied with the shorter needle than the longer needle—a greater proportion than the 27.9% of patients who preferred the longer needle over the shorter needle. The difference was primarily driven by injection comfort.⁵

Third, greater adherence with pen needles may offset increased costs by reducing hospitalization rates. In a study of 13,428 patients with diabetes, adherent patients using pen needles experienced significantly greater reductions in glycosylated hemoglobin levels than nonadherent syringe/vial users (P = .045). Although the average pharmacy costs were higher for pen users ($2923; P <.01), hospitalization rates were significantly lower by 0.36 hospitalizations per person per year (P <.01), and total health care costs were similar (P = .10).⁶

In a retrospective study of patients enrolled in Medicaid, investigators identified lower annualized health care costs in patients using insulin pens versus patients using needle/syringe insulin administration ($14,857 compared with $31,765; P <.05). Hospital costs, diabetes-related costs, and outpatient costs were all reduced significantly (P <.05).⁷

Practical Cost Considerations

The storage requirements of insulin are an important practical cost-savings consideration for pharmacists and third-party payers. Insulin pens contain 3 mL of insulin solution. Premixed insulin pens and NPH insulin pens containing regular human insulin can be stored at room temperature for 10 to 14 days, and pens containing insulin analogs (ie, lispro, aspart, glulisine, glargine, and detemir) can be stored for 28 or more days. This contrasts with vials of insulin, which contain 10 mL of medications, more than 30 times the amount of medications in a pen needle, and can be stored at room temperature for 28 days, sometimes more, although the American Diabetes Association recommends limiting that amount of time to 1 month (Online Table).^1,2,7

Table: Storage Requirements for Insulins

Medication

Room-Temperature Stability Upon Opening

Pens containing neutral protamine hagedorn insulin (eg, Novolin N Pen, Humulin N Pen)

14 days

Pens containing premixed insulins (eg, Humalog, Humulin, Novolog)

10 days (Humalog and Humulin); 14 days (Novolog)

Pens containing rapid-acting insulins (eg, aspart, lispro, and glulisine), regular insulin supplied in a cartridge form for administration in a refillable insulin pen (eg, Novolog Penfill and Humalog Cartridge)

28 days

Pens containing long-acting insulins (eg, Lantus Solostar, Levemir FlexTouch)

28 days (Lantus Solostar); 42 days (Levemir FlexTouch)

Vials of insulin (10 mL; 100 units/mL)

Some as short as 28 days, but no more than 1 month (30 days) per the recommendation of the American Diabetes Association

^{Adapted from references 1, 2, and 8.}

These differences in storage considerations between insulin pens and insulin vials can sometimes result in wasted insulin. For example, a patient using 18 units of insulin glargine basal insulin (Lantus) each day may purchase a 10-mL vial for a cash price of $133, inject 18 units daily for 28 days, and use 5 mL of the 10-mL vial before having to discard the remainder. Half of the medication is wasted. Contrasting with this, a patient purchasing a box of 3 Lantus Solostar pens, each of which contains 3 mL of insulin glargine, can use 1 pen every 28 days. Although the cost of the box of Lantus Solostar pens is approximately $400, no medication is wasted, and the cost to insurers is similar to the cost of the vial.^7-10

Despite the fact that insulin pens incur no greater cost than vials for patients using fewer than 18 units of insulin daily, many state Medicaid programs will not cover the cost of insulin pens under any circumstances. To change this, state Medicaid programs must alter prior authorization policies so that patients who need small daily doses of insulin can receive insulin pens. This change would improve the convenience of insulin use for elderly patients with T2DM, reduce medical costs through improved patient adherence, and incur no additional medication- related costs to Medicaid plans.¹

Conclusions

Pen needles are more convenient to use, less painful, and result in better adherence and improved health outcomes for patients with diabetes than traditional pen/ needle/vial administration of insulin. By recognizing the adherence benefits and the potential cost savings opportunities for patients using low volumes of insulin, state Medicaid programs and insurance programs across the United States could save money and improve health outcomes for patients with T2DM by covering the cost of insulin pens.

Michael R. Page, PharmD, RPh, earned his PharmD from the Ernest Mario School of Pharmacy at Rutgers University. He has worked as a community pharmacist at CVS Pharmacy and is currently clinical editor in clinical and scientific affairs at Pharmacy Times.

References

• Pisano M. Overview of insulin and non-insulin delivery devices in the treatment of diabetes. P T. 2014;39(12):866-876.
• Papadakis M, McPhee S, Rabow MW, eds. Current Medical Diagnosis and Treatment 2015. 54th ed. New York, NY: McGraw Hill Medical; 2015.
• Ramadan WH, Khreis NA, Kabbara WK. Simplicity, safety, and acceptability of insulin pen use versus the conventional vial/syringe device in patients with type 1 and type 2 diabetes mellitus in Lebanon. Patient Prefer Adherence. 2015;9:517-528.
• Xie L, Zhou S, Wei W, Gill J, Pan C, Baser O. Does pen help? A real-world outcomes study of switching from vial to disposable pen among insulin glargine-treated patients with type 2 diabetes mellitus. Diabetes Technol Ther. 2013;15(3):230-236.
• Berard L, Cameron B, Woo V. Pen needle preference in a population of Canadians with diabetes: results from a recent patient survey. Can J Diabetes. 2015. doi: 10.1016/j.jcjd.2014.09.008.
• Ayyagari R, Wei W, Cheng D, Pan C, Signorovitch J, Wu EQ. Effect of adherence and insulin delivery system on clinical and economic outcomes among patients with type 2 diabetes initiating insulin treatment. Value Health. 2015;18(2):198-205. doi: 10.1016/j.jval.2014.12.016.
• Pawaskar MD, Camacho FT, Anderson RT, Cobden D, Joshi AV, Balkrishnan R. Health care costs and medication adherence associated with initiation of insulin pen therapy in Medicaid-enrolled patients with type 2 diabetes: a retrospective database analysis. Clin Ther. 2007;29:1294-1305.
• Grajower MM. How long can a vial of insulin be used after it is started: where are we 10 years later? Endocr Pract. 2014;20(2):188-190.
• Drugs.com. Lantus prices. www.drugs.com/price-guide/lantus. Accessed April 2015.
• Drugs.com. Lantus Solostar prices. www.drugs.com/price-guide/lantus-solostar. Accessed April 2015.