Insulin Pens: Improving Adherence and Reducing Costs

Michael R. Page, PharmD, RPh

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.

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.

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

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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.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.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.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 waysInsulin 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 studiesIn 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