Chapter 7: Parenteral Medication Administration

7.4 Subcutaneous Injections

Critical Thinking Exercises: Questions, Answers, and Sources / References

  1. Name four nursing considerations specific to SC insulin administration.


Guidelines for Administering SC Insulin
Insulin nursing considerations Additional Information
Insulin is considered a high-risk medication. Special care must be taken to ensure the correct amount of medication and type of insulin is administered, at the correct time. It is highly recommended to always have an independent double check prior to insulin administration. Always follow the standard for medication preparation at your agency.
There are specific syringes for insulin Insulin syringes have a needle attached. Insulin is always ordered and administered in units, based on a blood sugar reading and a diabetic insulin protocol (or sliding scale). Some hospitals have preprinted physician orders, and some hospitals have handwritten orders. Insulin syringes can come in 30-, 50-, or 100-unit measurements. Always read the increments (calibration) carefully.
Insulin can also be administered via other devices Insulin pens are one method for insulin administration. The pen consists of a syringe (pen), needle, and prefilled cartridge of insulin. It is essential that patients be taught how to use injection pens so they understand the technology. One pen per person to avoid risk of BBF exposure. The needle has to be primed prior to administration. In hospital settings, needles with safety systems must be used. Due to the expense, persons using insulin pens at home can opt for a less expensive needle that doesn’t have the safety system in place.

A mini-infusion pump is a battery-operated machine that delivers medications in very small amounts to patients with controlled infusion times. The most common types of mini-infusion sets are insulin pumps or subcutaneous infusion devices. For more information on mini-infusion sets and volume-controlled sets, see Suggested Online Resources in section 7.8.

There are different types of insulin. There are rapid-, short-, intermediate-, mixed-, and long-acting insulins. For each type of insulin, it is important to know how the insulin works and the onset, peak, and duration of the insulin. Recognizing and responding to hypoglycemia is essential.
Administering two different types of Insulin. If a patient is ordered two types of insulin, some insulins may be mixed together in one syringe. Many insulins MAY NOT be mixed together. Do not mix Lantus (Glargine) or Levemir (Determir). If administering cloudy insulin preparations (Humulin – N), gently roll the vial between the palms of your hands to re-suspend the medication.
To get into good habit, always draw up the short acting (clear) insulin before the cloudy insulin. You cannot contaminate either vial. If too much insulin is drawn up from the second vial, discard syringe and start again. Insulin orders may change daily and even throughout the day. Always ensure the most current orders are being followed.
Know about rotating injection sites. Injection site rotation is no longer necessary, as newer insulins have a lower risk for hypertrophy of the skin. Typically, a patient will pick one anatomic area (e.g., upper arm) and rotate the injection sites within that region to maintain consistent insulin absorption from day to day. Insulin absorption rates vary from site to site. The abdomen absorbs the fastest, followed by the arms, thighs, and buttocks.
Know when to administer insulin. Insulin dosing is often based on blood glucose levels. Knowing the onset, peak, and duration of insulin is critical to helping the patient to maintain normoglycemic levels. If giving insulin, always ensure the patient is not nauseated, is able to eat, and that food is arriving before the insulin starts working.

Typically, short- or rapid-acting insulin is given 10 to 15 minutes before meals. Intermediate- or long-acting insulin may be given twice daily, at breakfast and dinner or breakfast and bedtime.

Measure blood sugar levels and food intake. Insulin injections are based on blood sugar values and on when the patient will eat. The timing of an insulin injection is critical to ensure the patient maintains normal blood glucose levels.

Data sources:

Canadian Diabetes Association. (2013). Canadian Diabetes Association Clinical Practice Guidelines Expert Committee. Clinical practice guidelines for the prevention and management of diabetes in Canada. Canadian Journal of Diabetes, 37(1), s1-s212.

Perry, A., Potter, P., & Ostendorf, W. (2017). Clinical skills and nursing techniques (9th ed.). St. Louis, MO: Elsevier-Mosby.


In addition:

  • Insulin is stored in the refrigerator. When a vial is in use, it should be at room temperature. Do not administer cold insulin. Check agency policy for how long a vial can be used after being opened. It is usually 30 days.
  • Patients who take insulin should monitor their blood sugar (glucose) levels as prescribed by their health care provider.
  • Vials of insulin should be inspected prior to use. Any change in appearance may indicate a change in potency.
  • Use the type of insulin prescribed. Do not change the type unless ordered by a health care provider.
  • Allow patient to choose site for injection. A patient may self-administer insulin if it’s determined to be safe and in the patient’s best interest.
  • All health care providers should be aware of the signs and symptoms of hypoglycemia. Signs and symptoms include fruity breath, restlessness, agitation, confusion, slurring of words, clammy skin, inability to concentrate or follow commands, hunger, and nausea. The patient may complain of blurred or double vision. Late signs include unconsciousness. Hypoglycemia is a medical emergency. Always have an emergency diabetic kit available. If a conscious diabetic patient appears to be hypoglycemic or has a blood sugar (glucose) reading of 4 mmol/L or lower, give glucose, such as sucrose tablets, solution, or juice. Follow agency policy regarding hypoglycemic reactions.

Copied from: Anderson, R. (2018). Clinical Procedures for Safer Patient Care – Thompson Rivers University Edition. Adapted from Clinical Procedures for Safer Patient Care by G. R. Doyle and J. A. McCutcheon. Chapter 7.4 Subcutaneous injections


2. Describe two situations where an indwelling subcutaneous device is warranted.


  • Frequent subcutaneous injections
  • Subcutaneous infusion

3. Name four safety considerations associated with giving meds via an indwelling subcutaneous catheter.


a, They are inserted following principles of asepsis, and the sites dressed according to agency protocol. A semi-permeable transparent dressing allows frequent and accurate assessment of the insertion site.
b. How long an indwelling SC device remains in situ will depend on many factors including patient characteristics, volume of fluid infused, medication, and integrity of the site.
c. Sites should be rotated to prevent tissue damage. This includes:

  • every 7 days and as needed for intermittent medication administration. Some sites advise up to 14 days (RCH, 2014). Check your agency protocol.
  • every 24 to 48 hours or after 1.5 to 2 litres of solution has infused (Saskatchewan Health Authority, 2018).
d. Sites that are red, tender, edematous, bruised, bleeding, burning, leaking, have blood in the tubing and/or have a displaced cannula need to be removed and re-established.
e. Each site is designated for one particular purpose (i.e., one medication only per site).
f. When used for intermittent medication administration, because there is a small volume associated with the device called the dead space, the initial dose must include a larger volume to account for the volume in the dead space after the first dose is administered. Check your agency protocols to determine this volume (Saskatchewan Health Authority, 2018; RCH, 2014)
g. Each site is labelled with the date it was initiated, the medication name and concentration used, and the nurse’s initials
h. If necessary, change the end cap to one that can be accessed without needles.

Sample Learning Activities

  1. A small case study on Insulin Administration

Situation: At 0600 Charlie administers Aspart 15 units and NPH 6 units subcutaneously.  The following questions relate to this scenario.

1. Why does Charlie need 2 different types of insulin?

Answer: Aspart is rapid acting and will help to lower blood sugar when simple carbohydrates begin to metabolize. As carbohydrates metabolize they elevate blood glucose levels. Aspart is considered bolus insulin and is meant to mimic the rapid release of insulin that occurs when blood glucose levels rise when we eat / drink.

NPH is intermediate insulin and helps to metabolize complex carbohydrates, fats and proteins. As these things metabolize blood glucose levels elevate. NPH is considered a basal insulin meant to mimic the slow release of insulin that occurs throughout the day in persons with a healthy pancreas.

The combination of rapid and intermediate insulin is intended to maintain normal blood glucose levels.


2. Charlie asks: why do I need 2 different kinds of insulin? What is the nurse’s best response.

a. You need 2 different kinds of insulin because one is fast and one is slower

b. You need 2 different kinds of insulin because they will keep your blood glucose normal

c. You need 2 different kinds of insulin to maintain blood glucose levels as your body metabolizes carbohydrates, proteins and fats.

d. You need 2 different kinds of insulin to prevent complications of diabetes

Answer: all responses are true. The 3rd response is most accurate because it gives the most detail.


3. If Charlie is at risk of hypoglycemia when his insulin peaks, what time is that?

Answer Aspart insulin peaks in 45-60 minutes, he is at risk just before 0700. If NPH peaks in 8 hours, he is at risk around 1400h.


4. What are S&S of hypoglycemia? 

Answer: drowsiness, lethargy, cool clammy skin, headache, hunger, blurred vision,


5. List the sites in terms of rate of insulin absorption fastest to slowest. Arm, Thigh / buttock, abdomen    Answer: abdomen, arm, thigh / buttock



Diabetes Canada (2018). Diabetes Canada Clinical Practice Guideline.

Lilley, L. L., Rainforth Collins, S.,  Snyder, J. S., Collins, S., & Swart, B. (2016). Pharmacology for Canadian health care practice (3rd ed.). Toronto, ON: Elsevier Canada..

  1. Name 4 nursing considerations specific to SC insulin administration.

Answer: choose a site free of lesions and bony prominences and where there is adipose tissue (back of arms, abdomen, thighs); use a short needle (half of the width of a skin pinch; inject at 45 degrees / 90 degrees if there is ++ adipose tissue; no need to aspirate because adipose tissue is poorly vascularized and thus very small risk of injecting into a vein; know blood glucose level prior; know pharmacodynamics of the insulin to be able to anticipate onset, peak and duration; know S&S of hypoglycemia and how to treat


2. Name 4 safety considerations associated with giving meds via an indwelling subcutaneous device.

Answer: each device is to be used for 1 med only; first dose requires slightly larger volume to account for the deadspace in the device and needleless cap; change to needless cap if necessary to avoid use of needles and thus to reduce risk of needle stick injury; use chlorhexidine on skin prior to insertion; Use TSM dressing to allow observation of the insertion site and to allow skin to breathe

Sample Quiz Questions


1. The first thing to do after a needle stick injury is:

a. Tell someone

b. Wash the site with soap and water

c. Wash the site with alcohol based handrub

d. Report to the emergency department


Answer: B. The key to answering this question is the word ‘first’ while the nurse should do all of these things, except C, the first thing is to wash the site with soap and water.


Source: Centers for Disease Control (CDC). (2015). Injection safety


2. Keeping the bevel up is important in all parenteral medication administration (true / false)

Answer: false. Bevel up is only necessary when administering medications intradermally


3. Which of the following are correct in relation to medication administration? (select all that apply)

Distractor Answer
a. When preparing medications from a vial, the top of the vial should be cleaned with alcohol  and allowed to dry. correct
b. There is risk of being cut with glass when breaking open an ampule correct. The nurse should use an ampule breaker or wrap a alcohol swab package around the neck of the ampule
c. Blunt fill needles are used to filter glass when preparing meds from a vial incorrect. Blunt fill needles are different than blunt fill filter needles. Vials do not involve glass breaking and as such do not require a filter
d. Ampules and vials should be single use only whenever possible correct

4. When administering heparin subcutaneously, the nurse should (select all that apply)

Distractor Answer
a. Administer into the deltoid site incorrect. The deltoid is a muscle. Heparin injected into muscle can result in bleeding and bruising
b. Massage the site after removing the needle incorrect. Massaging the site after a heparin injection  may cause tissue damage / bruising at the site
c. Choose a site free of lesions, moles correct. This is true for all SC and IM injections
d. Check for signs and symptoms of complications related to the heparin correct this will include bruising, bleeding
e. Check blood glucose prior to administration incorrect. Blood glucose is not affected by heparin, an anticoagulant
f. Aspirate prior to administration incorrect. Aspirating with SC injections isn’t necessary because adipose tissue is poorly vascularized and the risk of inadvertently injecting the medication into the bloodstream very low

Source: Perry, A., Potter, P., & Ostendorf, W. (2017). Clinical skills and nursing techniques (9th ed.). St. Louis, MO: Elsevier-Mosby.


5. With the following image(s) read the syringe to determine the correct volume.

Figure 7.1

Answer: 48 units


Attributions: Figure 7.1 Insulin syringe in disassembled form by is used under a CC BY  4.0 International license.


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