Proper Injection Technique Ensures Positive Outcomes Among Patients With Diabetes


Effective glycemic control is needed for the successful management of type 1 diabetes (T1D) and type 2 diabetes (T2D). The American Diabetes Association recommends individualization of glycemic targets based on established risk factors and disease features.1 Without optimized management, hyperglycemia can lead to microvascular complications (eg, retinopathy, neuropathy, and nephropathy) and macrovascular complications (eg, coronary artery disease, stroke, and peripheral vascular disease).1,2 A hemoglobin A1c (HbA1c) goal of less than 7% is appropriate for most adult patients with T1D and T2D to reduce the risk of primary and secondary diabetes-related complications.1

Insulin therapy may be initiated to regulate glycemic levels and help patients achieve their HbA1c targets. Health care professionals (HCPs) and patients can share in decision-making and initiate an insulin therapy option with the appropriate insulin delivery system and type of insulin. Selection considerations may include cost, patient-specific preference, and overall dexterity for injections.1

Considerations of Needle Sizes and Insulin Injection Device: Pens and Syringes

Insulin syringes and pens are both safe and effective options for maintaining glycemic control. Results from clinical trials of insulin pen use in patients with diabetes have shown equivalence or small improvements in glycemic outcomes compared with use of vials and syringes.1 Therefore, the most appropriate insulin delivery system for each patient can be selected.

Several manufacturers have made available insulin syringes and pen needles in different lengths and gauges (Table).3 The gauge of the needle is an important consideration. For example, thicker needles can administer insulin faster, but they are associated with more pain when compared with a thinner needle. Thinner needles are represented by higher gauges, with current gauges available from 22G to 33G.1 Needles with the shortest length and highest gauge may be considered to help reduce pain associated with injecting insulin and to ensure that the needle is only penetrating the subcutaneous (SC) space.4

The safest needle lengths that are currently available are 6 mm for a syringe and 4 mm for a pen.4 Among the pen and syringe needle sizes, these shorter length needles provide the lowest risk for intramuscular (IM) injection regardless of patient age, sex, body mass index (BMI), or obesity status.1,4 Different needle lengths require different administration techniques. A 6 mm–length syringe needle requires injection at a 45° angle or into lifted skin to ensure that insulin is injected within the SC space. A 4 mm–length pen needle can be inserted at a 90° angle to the skin. Lifted skin is not required with this pen needle length for most patients, as it poses minimal risk for penetrating the muscle; however, for pediatric patients 6 years or younger or adults with a low BMI, a skinfold is needed to ensure that the needle remains in the SC space.4

Patient Education on Insulin Administration and Injection Technique

Education on the proper insulin injection technique is needed to help patients with diabetes achieve their glycemic targets and optimize outcomes of insulin therapy.1 Moreover, continued education by HCPs can improve overall management of glycemic levels by promoting insulin adherence, proper injection technique, and positive perceptions of diabetes management.5

Complications of Improper Injection Technique

Improper injection technique is associated with risks of poor glycemic outcomes, glycemic variability, and complications, such as lipohypertrophy.1

Insulin must be injected into a correct location of the body, which includes the SC space of the buttock, thigh, upper arm, or abdomen. Shorter length needles provide the lowest risk for IM injections, which has been associated with unpredictable insulin absorption, glycemic variability, and hypoglycemic events.1,4 These effects may occur because the absorption rate of insulin via IM injection varies depending upon the activity of the muscle (ie, the rate increases from resting to active in exercising muscle).4

Lipohypertrophy presents as soft, smooth, elevated areas in the skin.1 It is an accumulation of SC fat that can occur in response to multiple injections at the same site or reuse of needles. It is estimated that at least 50% of all insulin-injecting patients are affected by lipohypertrophy.1,6 To prevent the development of lipohypertrophy, insulin injection sites must be continuously rotated; repeated injections into the same site or affected sites should be avoided. Repeated injection into the same site can reduce insulin absorption, increase glycemic variability, and cause hypoglycemic episodes.1,6

Counseling on Proper Insulin Injection Technique in the Pharmacy

As part of the diabetes care team, pharmacists have the opportunity to work closely with patients and providers to help improve patient glycemic outcomes. Pharmacists are accessible HCPs who are available to patients and their caregivers throughout the diabetes health care journey. Pharmacists have an opportunity to provide initial and continuous education that reinforces proper insulin injection technique at each visit to the pharmacy for insulin therapy or supplies.

Before Administration

Before each insulin injection with a pen or a syringe needle, the injection site on the body should be inspected, disinfected, and freed from clothing or obstacles. The injection site should be a different area of the body than previously chosen. A new, unused, clean needle should be used for each injection. Needles are not designed to be used more than once; patients should understand the risks of complications associated with lack of sterility and dullness of the needle after a single use.4

Pen vs Syringe Insulin Injection Steps

When providing patients with education on proper injection with a pen, advise and reinforce that they should follow these steps4:

  1. The pen should be primed before injection to ensure adequate flow.
  2. The needle should be inserted into the skin before the thumb button is pressed to administer medication.
  3. The pen needle should remain in the skin for 10 seconds after insertion to prevent any medication leakage, and pressure on the button should be maintained until the needle is withdrawn from the skin to prevent aspiration of tissue into the cartridge.
  4. After use, the needle should be removed from the pen and disposed of properly and immediately to prevent air or other foreign particles from entering the pen cartridge and avoid medication leakage, both of which can lead to dose discrepancies.

For patients who inject insulin with a syringe and vial, provide the following steps to support proper injection technique4:

  1. Confirm that the correct insulin syringe has been selected for the chosen concentration of insulin.
  2. Ensure that an amount of air equivalent to the insulin dose is drawn into the syringe and expelled into the vial to allow for withdrawal of the insulin.
  3. Withdraw insulin from the vial. Note that if the withdrawn insulin has visible air pockets, the syringe should be tapped gently to dislodge the air pockets, and the plunger should be readjusted to expel the air out.
  4. After the plunger has been completely depressed, the syringe needle can be removed. Unlike with pen administration, the syringe needle does not need to remain under the skin for 10 seconds.
  5. The needle should be removed from the syringe and disposed of properly and immediately to prevent air or other foreign particles from contaminating the medication or syringe and leading to dose discrepancies.

Continued Patient Education

Pharmacists can ensure that patients are continuously and repeatedly educated on pen or syringe injection technique to manage glycemic levels and improve overall outcomes. Moreover, pharmacists can monitor patients for complications (eg, hypoglycemia, hyperglycemia, and lipohypertrophy) and provide information on how to avoid those adverse outcomes by reinforcing the importance of proper injection technique.1


1. American Diabetes Association Professional Practice Committee. Standards of Medical Care in Diabetes-2022. Diabetes Care. 2022;45(suppl 1):S1-S264.

2. Fowler MJ. Microvascular and macrovascular complications of diabetes. Clin Diabetes. 2008; 26(2):77-82. doi:10.2337/diaclin.26.2.77

3. The BD family of diabetes products reorder numbers. In: BD—Your Diabetes Injection Experts. Beckton, Dickinson and Co. 2012.

4. Frid AH, Kreugel G, Grassi G, et al. New insulin delivery recommendations. Mayo Clin Proc. 2016;91(9):1231-1255. doi:10.1016/j.mayocp.2016.06.010

5. Selvadurai S, Cheah KY, Ching MW, et al. Impact of pharmacist insulin injection re-education on glycemic control among type II diabetic patients in primary health clinics. Saudi Pharm J. 2021;29(7):670-676. doi:10.1016/j.jsps.2021.04.028

6. Hirsch LJ, Strauss KW. The injection technique factor: what you don’t know or teach can make a difference. Clin Diabetes. 2019;37(3):227-233. doi:10.2337/cd18-0076

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