What is Insulin?
Insulin is a hormone produced by the pancreas that allows the body to use blood sugar for energy. Carbohydrates, a type of nutrient found in starchy foods such as bread, noodles, potatoes and rice, are converted into sugar and absorbed into the bloodstream. Insulin allows sugar from the bloodstream to enter the body cells and be used to create energy or be stored for future use.
People with diabetes are unable to fully use the sugar in their bloodstream either because their bodies do not make enough insulin or the cells do not respond well to insulin, a situation known as insulin resistance. Hence, they would need more insulin to get the same effects.
Insulin Therapy
There are two main groups of patients with diabetes and their treatment could be different.
- Type 1 Diabetes Mellitus (T1DM) requires the use of insulin and the patient needs to control their diet.
- Type 2 Diabetes Mellitus (T2DM) patients may be treated with oral medications and need to control their diet. In some T2DM patients, they may also require insulin injections.
Insulin is injected into the fatty tissue that is between the skin and muscle layer.
Starting on insulin when already on oral tablets for T2DM patients
T2DM is a progressive illness. This means that what you did at the beginning to control your condition through your diet, exercise or medications may change over time.
As your diabetes progresses, the management of your condition can change from diet and exercise alone, to adding oral diabetes medications. Patients who have had diabetes for a long time may naturally find that they progress to a combination of oral diabetes medications and insulin.
Some T2DM patients might feel that once they have started insulin, it could mean that their condition is now very serious or they have “failed” in controlling their diabetes. However, it is important to understand that this is a natural progression of the disease. If your diabetes is not controlled, it can lead to serious health complications such as an increased risk of heart disease and eye or kidney problems.
If you are on insulin, you should know how to:
- Measure out your insulin doses
- Inject insulin yourself (and not rely on others) as far as possible
- Adjust your diet and activity to your insulin injections
Types of Insulin
There are several types of insulin. They differ mainly in how quickly they start to lower blood sugar once injected, and how long their effects last in the body.
| Type | When to take it | When the medication starts working after you have injected it | How long does the medication effect last after you have injected it |
Rapid-acting
| Immediately before a meal | 10-20 minutes | 2-4 hours |
Short-acting
| 30 minutes before a meal | 30 minutes | 6-8 hours |
Intermediate-acting
| Before breakfast and/or at bedtime | 1-3 hours | 16-24 hours |
Long-acting
| Daily at the same time (eg. bedtime) | 3-4 hours | Variable. Up to 24 hours for Levemir®, Lantus® and Soliqua®. May last more than 24h for Toujeo® and Tresiba®. |
Pre-mixed These are mixtures of rapid/ short-acting and intermediate/ long-acting insulins
| Variable, inject before meals. Refer to your medication label for timing of injection for your specific type of pre-mixed insulin | Variable | Variable, 14 to more than 24 hours |
Low blood sugar (hypoglycemia) is more likely to occur around the time of maximum action. High blood sugar (hyperglycemia) is more likely to occur before the insulin starts acting or when its action is ending.
* Soliqua® is a combination of long-acting insulin and lixisenatide (another type of diabetes medication class known as GLP1 agonist)
How to Inject Insulin
You may refer to this article for more details on how to select the area for injection of insulin and insulin injection techniques.
Handling and storage
Unopened insulin should be stored in the refrigerator (not in the freezer). Frozen insulin cannot be used. You should always keep at least one extra vial or pen of each type of insulin.
Once opened, the insulin vial or pen should be stored at room temperature and away from direct sunlight. The opened insulin vial or pen can be kept for four to six weeks depending on the type of insulin you use. Refer to your medication label to check how long you can keep your insulin for.
When you are travelling, carry your insulin and syringes with you. Do not put the insulin in your check-in luggage or in your car boot.
Discard the insulin if
- It has expired
- Your insulin has changed colour
- You are using a clear insulin and you find particles in it. Examples of clear insulins are Apidra, Novorapid, Actrapid and Glargine.
- You are using a cloudy insulin and you see white substances that remain at the bottom of the container after mixing even after you roll the vial or pen thoroughly. Examples of cloudy insulins are Mixtard and Novomix.
Side Effects
The most common side effect with the use of insulin is low blood sugar. If you inject insulin but do not eat on time, your blood sugar may become too low. Low blood sugar levels might also happen if you do not eat well or if you drink alcohol on an empty stomach while on insulin therapy.
Symptoms of low blood sugar include:
- Weakness
- Dizziness
- Hunger
- Sweating
- Trembling
- Blurred vision
- Walking unsteadily
- Fast heartbeat
If you experience any of these low blood sugar symptoms, do the following immediately:
Step 1: Check your blood sugar level with a home blood sugar meter (glucometer) if available. If your blood sugar level is less than 4 mmol/L, take 15 grams of fast-acting sugar such as:
- 3 glucose tablets or
- Half a glass of fruit juice (200ml) or
- 1 can of less sugar soft drink (330ml) or
- 3 teaspoons of sugar, honey or syrup
Step 2: Monitor yourself for 15 minutes. If you have a glucometer (home blood sugar meter), check your blood sugar level again after 15 minutes.
Step 3: If your blood sugar level is still less than 4 mmol/L or you still have symptoms of low blood sugar, you should take another 15 grams of fast-acting sugar as per Step 1.
If your symptoms do not go away, see a doctor or go to the hospital immediately.
Step 4: Take your meal or snack if your blood sugar level is 4 mmol/L and above after consuming the fast-acting sugar earlier on.
Inform your doctor about this during the next visit.
Other side effects include:
- Some patients may also experience mild pain, redness, bruising, swelling, a small lump or dent of the skin at the injection site.
- Do not reuse your needles, rotate injection sites within the recommended areas and use shorter needles (4mm or 6mm) to reduce the chances of developing such reactions.
- They also usually go away in a few days to a few weeks.
- See a doctor if you frequently experience this. Your injection technique may need to be reviewed.
- Rashes on the injection site or, in rare cases, all over the body
Disclaimer
Please take note that the above is not a complete list of all possible side-effects. If you have any concerns about your medication or if you have other side-effects that you think are caused by this medication, please consult your doctor or pharmacist. If you take more than the recommended dose, please seek medical advice immediately. The information provided on this page does not replace information from your healthcare professional. Please consult your healthcare professional for more information.
This article is jointly developed by members of the National Medication Information workgroup. The workgroup consists of cluster partners (NHG Health, National University Health System and SingHealth), community pharmacies (Guardian, Unity and Watsons) and Pharmaceutical Society of Singapore. The content does not reflect drug availability and supply information in pharmacies and healthcare institutions. You are advised to check with the respective institutions for such information.
Please visit www.moh.gov.sg/knowyourmeds and www.ndf.gov.sg for more information on medication.
Contributed By
- Pharmaceutical Society of Singapore