[Major points]

1. Insulin pen is portable, it is easy to complete the injection by turning the dose and pressing the button.
2. By following the steps, injection of insulin can be correctly and effectively performed.
3. Before using a mixed-type insulin, shake and rotate the pen to ensure even mixing of the insulin.
4. Prior to use, it is necessary to check the quality and expire date of the insulin.
5. The injection site should be rotated, and the needle should not be reused.

Why is insulin pen injection necessary?

Insulin injections are used to control blood glucose, and an insulin pen is a type of device that is pre-filled with insulin. Every time when an injection is needed, you can simply attach the needle and adjust the dose by using the dose setting button and pressing the injection button to complete the injection. Once the insulin is used up, the insulin pen can be discarded. An Insulin pen is convenient to use, easy to carry while you are traveling.

Who needs to use it?

The treatment of diabetes consists of aspects: diet, exercise, and medication. Generally, diet and exercise adjustments are made initially. If glucose control is still not satisfactory after diet and exercise modifications, medications well be required. Medical theray may involve oral hypoglycemic drugs or insulin. When insulin therapy is deemed necessary after evaluation by a physician, the use of an insulin pen can be considered for insulin injection to achieve better blood sugar control. (More information: Care of Patient with Diabetes Mellitus)

What supplies do I need to prepare?

Insulin pen prescribed by the doctor, pen needle, 75% alcohol swabs (Figure 1).

Figure 1 Preparation of supplies

How should I proceed?

1. Before injection: 
   1. Preparations.
   2. Wash hands and dry them.
   3. Choose the correct insulin pen:
      • Insulin pen can be roughly divided into rapid-acting, long-acting and premixed suspension according to the speed and length of action time after subcutaneous injection. The common types of insulin pens as follows(Figure 2). Please use the correct insulin pen according to the doctor's instructions.
        
        Figure 2 Types of insulin pens
      •  After selecting the pen needle, twist off the pen cap and check if there is enough insulin in the pen.
      • Check the expiration date of the insulin and inspect its appearance for any signs of spoilage, impurities, crystals, or other abnormalities.
      • If you are using a mixed type of insulin (such as Novomix, Humalog Mix-25 or Mix-50), please roll the insulin pen between your palms and gently turn the syringe up and down at least about 20 times before injection to mix the insulin evenly.
         
2. To begin the injection:
   1. Disinfect insulin pen: Use alcohol swabs to disinfect the rubber film of insulin pen.
   2. Install the needle:
      • Install a new pen needle just before each injection. 
      • After tearing off the protective sheet of the needle cover of the pen needle, align the needle head and turn it into the pen needle until it is tightly sealed.
      • When opening a new insulin pen, remove the air first: After inserting the needle, the needle is vertically upward, pull out the outer cover and inner cover of the needle, turn the dose setting button to 2 units, press the injection button to the bottom, and repeat this action until the insulin drips out. 
   3. Turn the dose setting button to the required dose unit and place the insulin pen in an easily accessible place for use.
   4. Select the injection site:
      • Injectable sites: the middle lateral upper arms of both sides, the bilateral abdomen beyond 2.5 cm from the navel, the upper 1/3 of the outer thighs of both sides, etc. (Figure 3).
        
         Figure 3 Injection sites
      •  After selecting the injection site, check for lumps.
      • In order to avoid the formation of hard lumps due to fat enlargement, which will affect the absorption, the injection sites need to be rotated, and the distance between the injection points should be about one finger width.
   5. Disinfect the skin, fully insert the needle:
      • Sterilize the injection site with an alcohol swab (circular disinfection with a diameter of 5cm from the middle).
      • Pick up the insulin pen(with a 4 or 5mm needle, you don’t need to pinch the injection site; if you use an 8mm needle, you need to pinch the injection site with your thumb and index finger), insert the needle at 90° (vertical), until the needle is completely inserted into the subcutaneous tissue, and then press the injection button all the way down, stay under the skin for 10-15 seconds to ensure that the dose is fully injected, pull out the needle, and gently press the injection site with an alcohol swab, be careful not to rub it.
3. After injection:
   1. Throw away the needle and cover it: loosen the needle and pull it out, put it into a hard container, and hand it over to the medical staff when returning to the clinic, and cover the insulin pen with the cap.
   2. Eat after the injection: Eat within 10-15 minutes after injecting rapid-acting or mixed insulin (Novorapid, Apidra, Novomix, Humalog Mix-25 or Mix-50) to avoid hypoglycemia. 

1. Storage of insulin pen:
   1. Unopened insulin can be stored in the refrigerator at 2-8°C until the expiry date.
   2. Insulin that has been opened can be stored at room temperature (if the room temperature exceeds 30°C, it is recommended to store it in the refrigerator). The date of opening is marked on the bottle, and the shelf life is 28 days. Long-acting Levemir, Toujeo can be stored for 42 days.
2. Pen Needle:
   1. Used needles cannot be reused and should be discarded immediately.
   2. The used needles should be collected in a hard and impenetrable container with a cover, and should not be discarded at will to avoid needle stick injuries.
3. If there is redness, swelling, heat or pain at the injection site, please seek medical attention as soon as possible.
4. During insulin treatment, self-monitoring of blood sugar is required regularly and return visits, and have backup insulin, in case of emergency.
5. If you still have problems with insulin pen injection after returning home, you can go to the  endocrinology & metabolic clinic or the diabetes integrated care clinic for inquiries:
   1. Diabetes integrated care outpatient location: the third floor of the second outpatient clinic.
   2. Clinic hours: Monday to Friday: 08:30-12:00am; Tuesday, Friday: 13:30-17:00 pm.

References

1. Bahendeka, S., Kaushik, R., Swai, A. B., Otieno, F., Bajaj, S., Kalra, S., Bavuma, C. M., & Karigire, C. (2019). EADSG guidelines: Insulin storage and optimisation of injection technique in diabetes management. Diabetes Therapy, 10(2), 341-366. https://doi.org/10.1007/s13300-019-0574-x
2. Chin, G., & Robins, M. (2019). Teaching patients with type 2 diabetes to self-administer insulin. The Royal Australian College of General Practitioners, 48(5), 251-254. https://doi.org/10.31128/AJGP-11-18-4764
3. Ellis, K., Mulnier, H., & Forbes, A. (2018). Perceptions of insulin use in type 2 diabetes in primary care: A thematic synthesis. BioMed Central Family Practice, 19(70), 1-21. https://doi.org/10.1186/s12875-018-0753-2
4. Taiwanese Association of Diabetes Educators (2022). 2022 Core teaching materials of diabetes health education. Taiwanese Association of Diabetes Educators.
5. Taiwanese Association of Diabetes Educators (2021). Taiwan insulin injection guidelines- 2021. Taiwanese Association of Diabetes Educators.