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Module 6. Insulin Safety

INSULIN: A "HIGH ALERT" MEDICATION

Insulin is a hormone that is produced by the pancreas that allows cells in the body to take in the energy they need to function properly. Since the discovery of insulin in the 1920's, insulin therapy changed in many notable ways. Today, patients with type 1 diabetes mellitus (T1DM) rely on insulin replacement as the mainstay of therapy. It is also commonplace for patients with type 2 diabetes mellitus (T2DM) to use insulin as part of their treatment regimens, since, often, insulin secretion decreases over time in people with T2MD. Eventually, exogenous insulin will be necessary to compensate for the lack of natural insulin release and effectively control glucose levels. Currently, at least 30% of patients with T2DM use insulin.1

Insulin is considered a "high alert" medication by the Institute for Safe Medication Practices,2 because any errors made in insulin dosing and/or injection technique can lead to severe consequences for patients. Most importantly, insulin errors can lead to severe hypoglycemia, which can be fatal.3 Practitioners must, therefore, pay particular attention to patient education about insulin products and ensure that patients thoroughly understand the use of this medication and are comfortable with appropriate administration of recommended doses.

Insulin is principally available as an injectable product. (An inhaled form of insulin has recently become available, but it is not widely used at this time.) As such, insulin requires more attention to patient education than most oral medications. Many patients are concerned and fearful about starting insulin therapy; these apprehensions may stem from discomfort with needles, expectations of pain, or anxiety about the complexity of a new daily regimen. Proper education helps to allay these fears. It is, therefore, incumbent on the entire health care team to ensure that a patient has a thorough understanding of how to safely store and inject insulin and properly dispose of needles.

BASAL INSULIN AND BOLUS INSULIN: 2 APPROACHES TO GLUCOSE CONTROL

When a patient uses insulin, the most important thing he or she needs to understand is how often and how much insulin to use. Insulin is measured in units, and an insulin pen or a dedicated syringe for insulin delivery with unit markings is the only way injectable insulin should be administered. Patients must also understand what type of insulin they will be using, and how each variety of insulin works. For patients with T2DM, some practitioners initiate insulin therapy with a once-daily basal insulin regimen.4 Basal insulin is a long-acting insulin product that releases small amounts of "background" insulin over time. In normal physiology, the pancreas continuously secretes small amounts of insulin to help the body maintain a basal metabolic rate. Exogenous basal insulin regimens attempt to mimic this normal process. There are a plethora long-acting insulin options and the main differences among the products are the durations of action. The durations of basal insulins range from 12 to 72 hours, and some of the newer basal insulins in development may have even longer durations. The starting dose of basal insulin for a patient with T2DM is often 10 to 20 units of a basal insulin given at bedtime, but all insulin regimens are unique and adjusted to meet the needs of each individual patient. Doses for basal insulin are usually based on weight.4 Timing of the injections can vary from morning to afternoon or evening, but patients must be educated that whatever time they decide to administer their basal insulin injections, they should do so at the same time every day. This maintains consistent insulin absorption and allows effective steady state peaks of insulin.5

Several long-acting basal insulin products are available: insulins glargine, degludec, and detemir. These products have durations of approximately 24 hours in most patients and they release insulin slowly throughout the day. In some patients, however, twice-daily dosing may be necessary for several reasons. First, some formulations do not have expected durations of 24 hours; second, at low doses, insulins have shorter durations than at higher doses, and this is true even for insulin products that are developed and advertised to last 24 hours.

Insulins with intermediate durations of action can also be used to replicate basal insulin secretion. NPH insulin (Novolin N, Humulin N) lasts approximately 8 to 10 hours. The activity of intermediate-acting insulin peaks approximately 6 to 8 hours after injection, which, under some circumstances, provides coverage for meals consumed around that time. Patients should try to eat close to the time of the insulin peak or risk having low blood sugar. NPH insulin is a cloudy-appearing suspension, not a clear solution like other types of insulin, and NPH needs to be mixed or rolled (not shaken) before use. NPH insulin is also available in pre-mixed vials and pen devices in which NPH insulin is combined with regular human insulin (a shorter-acting product). The pre-mixed insulin is usually administered twice daily because of the duration of action of the NPH insulin.6

The other component of insulin therapy is bolus insulin. Normally, the pancreas responds to a glucose load (e.g., an intake of glucose or its precursors during a meal) by secreting insulin. Exogenous bolus doses of insulin are administered to mimic this physiological process of "covering" a meal. Some patients with T2DM use bolus insulin, but all patients with T1DM require it, in addition to basal therapy. If a patient is using different types of insulin, it is important to emphasize that he or she must always double check the dose and type of insulin he or she is using before injection. Currently available injectable mealtime insulins for bolus dosing include insulin apart (Novolog), glulisine (Apidra), lispro (Humalog), and regular human insulin (Humulin R). Insulins apart, glulisine, and lispro begin to work within approximately 15 minutes after injection; regular human insulin is used less frequently because it takes up to 30 minutes to take effect. Because patients are often instructed to inject regular insulin 30 minutes before they eat, this particular mealtime insulin carries an increased risk for hypoglycemia if the patient becomes distracted and forgets to consume a meal after injecting the insulin. Doses of mealtime insulins will depend on a patient's insulin sensitivity and how many grams of carbohydrate they consume at a given meal.

Bolus insulin preparations are meant to be used to cover meals or food intake. These insulin products are generally administered before or with a meal, depending on a patient's blood sugar levels. Because these are short-acting and rapid-acting insulin products, it is imperative that patients know they are only to be administered with meals. Insulin therapy can be confusing, especially to new users, so patient education is a significant factor in guaranteeing that patients with diabetes stay healthy and safe. Pharmacy technicians can assist patients with diabetes by asking open-ended questions to assess how well a patient understands his or her therapy.7

INJECTING INSULIN: KEY POINTS FOR PATIENTS

A patient using insulin must be comfortable measuring and drawing up the proper doses of insulin. There are 2 different ways a patient can measure and inject insulin. Many patients now use insulin pens, which makes insulin injections easier and simpler than in the past.8 There are, however, still patients who use vials of insulin and need to draw up doses using a syringe. Several important safety tips will keep patients safe and comfortable with insulin therapy:

1. The patient must verify and understand the dose to be administered. Insulin is measured in units and an insulin syringe should always be used when drawing up an insulin dose from a vial.

2. Patients with manual dexterity issues or vision problems will likely find that an insulin pen is easier to use than vials and syringes. On a pen, a dose is "dialed up" using a dosage dial generally found at the base of the pen device. Patients must know how to read the dose through the dosing window of the device.

3. Insulin syringes are available in 3 sizes: 3/10 ml, ½ ml, and 1 ml. The best way to determine if a patient is using the correct syringe size is to evaluate the dose of insulin. If the insulin dose is 30 units or less, the 3/10-ml syringe is best; if the insulin dose is between 31 and 50 units, the ½-ml size is best; and the 1-ml syringe should be used for doses higher than 50 units.

4. Current recommendations for needle size have been evaluated in several studies, and it has been found that short needles (4 mm in length) are best for most patients. This size makes it easy for patients to inject only into the subcutaneous tissue and to avoid injecting into muscle.9 Patients with larger arms may require longer needle lengths; lean patients may require shorter needles.

5. Avoid sharing or reusing syringes. Sharing and reusing needles increases the risk of infection.10

6. If a patient is using 2 types of insulin in the same syringe, he or she must always draw up the shorter-acting insulin into the syringe first. This is not a frequent practice, since pre-mixed insulins containing an intermediate-acting and a rapid-acting insulin (e.g., Novolog 70/30, Humulin 70/30) are readily available. Patients may mix insulin if they use NPH and regular insulin together.

7. Before injecting NPH or intermediate-acting insulin products, patients must roll the vial between the palms a few times, or, in the case of a pre-filled pen, rock it gently back and forth. This will ensure that the concentration of the product is uniform before injection. Never shake insulin products.

8. To avoid insulin leaking out at the injection site, patients can count to 10 after injecting insulin before withdrawing the needle.

There are additional points that health care professionals must remember when ordering, dispensing, and administering insulin. First, insulin orders should not be abbreviated. "Units" should be clearly spelled out so it is not confused as a number: "U" is often misinterpreted as a "0." Also, the order "6 IU" can be misinterpreted as 61 units instead of 6 units. (In this example, the unit of measurement is also incorrect: "international units" are not used to measure insulin.)

Be careful of pairs of "sound-alike" insulin products, such as Novolin/Novolog and Humulin/Humalog. These medications can be easily confused with each other. In the hospital setting, there have also been reports of fatalities due to heparin and insulin mix-ups. Errors can easily occur if orders are not interpreted correctly,11 so all health care professionals involved in the medication use process must read all orders carefully and have multiple checks in place to verify the accuracy of all insulin products prescribed and administered.

Insulin injection sites

In addition to understanding how to measure the dose, patients must know how and where to inject insulin safely and effectively. If proper injection technique is not followed, inaccurate insulin dosing can occur due to poor absorption of insulin.12 This can lead to erratic blood sugar levels and even hospitalization in some extreme instances.

Insulin is self-administered as a subcutaneous injection, which means it is injected just under the skin. (In hospital settings, regular insulin may be administered intravenously.) Subcutaneous administration is best accomplished by gently pinching a piece of skin (such as under the arm or on the side of the thigh) and injecting the insulin. This avoids injecting into the muscle. However, with short needles (e.g., 4 mm in length), patients can often inject at a 90-degree angle without pinching the skin.

There are 3 sites that are commonly used for insulin injections: the arm, the abdomen, and the thigh. The buttocks can also be used, but a caregiver would be more likely to use this area as an injection site than a patient, because a patient cannot easily inject themselves in the buttocks. Some people prefer using the abdomen for insulin injections because there is usually extra skin available and it is easy to visualize the injection site. Studies have shown that different injection areas allow different rates of insulin absorption, and the abdomen has the fastest absorption rate.13 This information may be helpful when a patient has concerns about fluctuating blood sugar levels after varying injection sites.

Patients should avoid injecting insulin close to the belly button or near moles or scars. Injecting insulin in locations such as these can lead to ineffective absorption of insulin.14 Areas that contain a lot of blood vessels, such as the inner thighs, should also be avoided, because injecting in such sites can cause pain and possible bleeding. Patients should also avoid injecting in an area that they will be exercising, such as the arm, if they will be playing golf or tennis shortly after the injection. Exercise may cause insulin to be absorbed too rapidly.15

It is important to stress to patients that they should rotate injection sites regularly to avoid issues such as tissue irritation, erratic absorption of insulin, and infections.16 It may be helpful for patients to keep a journal or diary to keep track of where they are injecting. This may be especially important for older patients with memory issues.

INSULIN STORAGE

Proper storage of insulin ensures that the insulin maintains its effectiveness. Insulin that is not being used should be stored in the refrigerator. Any insulin vials that are "in use" can be stored outside of the refrigerator for approximately 1 month. (Always check manufacturer product inserts for exact storage requirements.) Most insulin pens can be stored outside of the refrigerator for 7 to 28 days. Insulin that is cold can produce a more painful injection than room-temperature insulin.17

Avoid exposing insulin products to extreme heat or cold. Insulin is a protein and this makes it subject to degradation or breakdown in extreme temperatures.18 Suggest that patients traveling with insulin use insulated travel bags with an ice pack to keep the insulin from getting too hot. Conversely, if cold weather is a factor, it is important to keep insulin products from freezing. Additionally, keep insulin products away from direct sunlight; this can also cause a breakdown of the protein. Any time a patient questions the effectiveness of his or her insulin, ask him or her how the insulin is stored and carried.

PROPER NEEDLE DISPOSAL

In a single year, approximately 9 million syringe users administer more than 3 billion injections outside traditional health care facilities. Nearly two-thirds of these people who self-administer insulin at home have diabetes; other circumstances that necessitate self-injection of medications include infertility treatments and anticoagulation therapy. Patients may not be aware of safe disposal methods for used needles and syringes and they may simply throw the used needles in the trash or flush them down the toilet. This practice poses a serious risk of injury and infection to anyone who encounters the used products and devices.19

Help patients and caregivers identify a sharps disposal container that they can use. Red "sharps containers" are usually sold in pharmacies. This is the best option for needle disposal, but patients may be unwilling to incur the added expense of a regulation sharps container. Additionally, patients may believe that throwing a needle in the regular trash is safe. In many cases, sharps are disposed of improperly because patients are not provided any guidance by their health care team on proper needle disposal. Therefore, it is incumbent on pharmacy professionals and other health care team members to teach patients and caregivers how to safely dispose of used needles. In 2004, the Environmental Protection Agency, in a collaborative effort with the Coalition for Safe Needle Disposal, published a set of guidelines for proper needle disposal outside of a hospital or health facility setting. The guidelines emphasized the importance of not disposing of sharps directly in the household trash.19

If a patient has no access to a red sharps container, a heavy-duty plastic container such as a laundry detergent bottle may suffice. State and local agencies have different laws and requirements for how to dispose of these improvised sharps containers. Refer patients to the local health department for additional information.20

INSULIN WITHOUT A PRESCRIPTION

Several insulin products that previously required a prescription can now be purchased without a prescription: regular insulin (Novolin R, Humulin R), NPH insulin (Novolin N, Humulin N), and combination products (Novolin 70/30, Humulin 70/30). These products can be sold in vials, but they are not available in pen devices without a prescription. This improves access to insulin for patients with diabetes, but it also presents problems for patients who do not understand how to effectively and safely use insulin.  

Patients who purchase insulin without a prescription may not necessarily understand what type of insulin they need and how much to use. A patient may have stopped taking insulin and  decided to restart it on his or her own, without medical supervision. Patients from other countries who purchase insulin in the United States may not understand how insulin products differ from each other and from those available in other countries. Some people even "share" insulin, believing it is safe to treat themselves and others. It is an ongoing debate among health care professionals whether or not insulin should be available without a prescription, since insulin can cause serious health problems if used incorrectly and without proper supervision by a health care professional. Medication errors happen when insulin products are interchanged, such as when a patient administers long-acting insulin instead of short-acting insulin. Dangerously low blood sugars can result from such an error and cause serious, even fatal, consequences.21

Insulin syringes are, of course, a necessary component of injectable insulin therapy. Although many states do not require a prescription for syringes, some states still do, and other states have limits on quantities that can be purchased without a prescription. In Minnesota, New Jersey, and New York, for example, a person can purchase up to 10 syringes without a doctor's prescription under certain conditions. Some states have age restrictions for purchasing syringes, and some states require the purchaser to disclose the intended use for the syringe. Check with state regulatory agencies to confirm requirements for selling insulin syringes.22

CONCLUSION

The use of insulin requires patient and/or caregiver instructions on doses, measurements, injection techniques, and storage conditions. Pharmacy technicians are often the first point of contact for patients in a busy pharmacy, and one observation by an astute technician can potentially make a huge impact on a patient's life. If a patient is not sure how to use or inject insulin, alert a pharmacist that the patient may require additional counseling. Ask patients open-ended questions about their insulin therapy to ensure that they understand the proper use and administration of insulin:

  1. How do you dispose of your insulin needles/syringes?
  2. How did your doctor tell you to use the medication?
  3. Where do you store your insulin?
  4. How do you store your insulin while traveling?

References

  1. Houlden R, Ross S, Harris S, et al. Treatment satisfaction and quality of life using an early insulinization strategy with insulin glargine compared to an adjusted oral therapy in the management of type 2 diabetes: the Canadian IN-SIGHT study. Diabetes Res Clin Pract. 2007;78(2):254-258.
  2. ISMP's List of High Alert Medications. The Institute for Safe Medication Practices. www .ismp.org/tools/highalertmedications .pdf. Published 2014. Accessed November 22, 2016.
  3. Lipska KJ, Ross JS, Wang Y, et al. National trends in U.S. hospital admissions for hyperglycemia and hypoglycemia among Medicare beneficiaries, 1999 to 2011. JAMA Intern Med. 2014;174(7):1116-1124.
  4. Riddle M, Rosenstock J, Gerich J; for the Insulin Glargine 4002 Study Investigators. The treat-to-target trial: randomized addition of glargine or human NPH insulin to oral therapy of type 2 diabetic patients. Diabetes Care. 2003;26(11):3080-3086.
  5. Peyrot M, Barnett AH, Meneghini LF, Schumm-Draeger PM. Insulin adherence behaviours and barriers in the multinational Global Attitudes of Patients and Physicians in Insulin Therapy study. Diabet Med. 2012;29(5):682-689.
  6. Starke AA, Heinemann L, Hohmann A, Berger M. The action profiles of human NPH insulin preparations. Diabet Med. 1989;6(3):239-244.
  7. Newton C. Why basal-bolus insulin therapy may be the best choice for type 2 diabetes. Diabetes Health. https://www.diabeteshealth.com/why-basal-bolus-insulin-therapy-may-be-the-best-choice-for-type-2-diabetes/.Published November 27, 2007. Accessed December 12, 2016.
  8. Pisano M. Overview of insulin and non-insulin delivery devices in the treatment of diabetes. P T. 2014;39(12):866-876.
  9. Gibney MA, Arce CH, Byron KJ, Hirsch LJ. Skin and subcutaneous adipose layer thickness in adults with diabetes at sites used for insulin injections: Implications for needle length recommendations. Curr Med Res Opin. 2010;26(6):1519-1530.
  10. 2007 Guideline for Isolation Precautions: Preventing Transmission of Infectious Agents in Healthcare Settings. Atlanta, GA: U.S. Department of Health and Human Services and the Centers for Disease Control and Prevention. www.cdc.gov/hicpac/2007IP/2007isolationPrecautions.html. Updated 2010. Accessed November 22, 2016.
  11. Kaplan EH, O'Keefe E. Let the needles do the talking! Evaluating the New Haven needle exchange. Interfaces. 1993;23(1):7-26.
  12. De Coninck C, Frid A, Gaspar R, et al. Results and analysis of the 2008–2009 Insulin Injection Technique Questionnaire survey. J Diabetes. 2010;2(3):168-179.
  13. American Diabetes Association. Position statement: Continuous subcutaneous insulin infusion. Diabetes Care. 2004;27 Suppl 1:S110.
  14. Johansson UB, Amsberg S, Hannerz L, et al. Impaired absorption of insulin aspart from lipohypertrophic injection sites. Diabetes Care. 2005;28(8):2025-2027.
  15. Berger M, Halban P, Assal J, et al. Pharmacokinetics of subcutaneously injected tritiated insulin: effects of exercise. Diabetes. 1979;28 Suppl 1:53-57.
  16. Vardar B, Kizilci S. Incidence of lipohypertrophy in diabetic patients and a study of in influencing factors. Diabetes Res Clin Pract. 2007;77(2):231-236.
  17. American Diabetes Association. Position Statement: Insulin administration. Diabetes Care. 2004;27 Suppl 1:S106-109.
  18. torvick WO, Henry HJ. Effect of storage temperature on stability of commercial insulin preparations. Diabetes. 1968;17(8):499-502.
  19. Do's and Don'ts: Safe Disposal of Needles and Other Sharps Used At Home, AT Work, or While Traveling. U.S. Food and Drug Administration. http://www.safeneedledisposal.org/wp-content/uploads/2015/07/sharps_dos-and-donts.pdf. Published 2015. Accessed October 22, 2016.
  20. Turnberg WL, Jones TS. Community syringe collection and disposal policies in 16 states. J Am Pharm Assoc (Wash). 2002;42(6 Suppl 2):S99-104.
  21. Adlersberg MA, Fernando S, Spollett GR, Inzucchi SE. Glargine and lispro: two cases of mistaken identity. Diabetes Care. 2002;25(2):404-405.
  22. Taussig JA, Weinstein B, Burris S, Jones TS. Syringe laws and pharmacy regulations are structural constraints on HIV prevention in the US. AIDS. 2000;14 Suppl 1:S47-51..

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