Insulin helps the body move glucose from the blood into cells, where it can be used for energy. People with diabetes may need insulin because their body does not make enough insulin or cannot use it properly.
Missing an insulin dose can cause blood sugar levels to rise. How much they rise depends on the type of insulin missed, the amount prescribed, the person’s diabetes, food intake, activity, and other factors.
For some people, missing one dose may mainly result in temporarily high blood sugar. For others, especially people with type 1 diabetes, missing insulin can become serious because too little insulin can cause ketones to build up and may lead to diabetic ketoacidosis, also known as DKA.
In this blog, we explain the Side Effects of Missing a Dose of Insulin, including changes in blood sugar, warning signs, DKA risks, and when to seek urgent medical attention.
Key Takeaways
- Missing insulin can cause blood sugar levels to rise.
- The effects depend on the type of insulin, dose, and individual treatment plan.
- People with type 1 diabetes may be at risk of diabetic ketoacidosis when insulin is missed.
- High blood sugar can cause thirst, frequent urination, tiredness, and blurred vision.
- Do not automatically take extra insulin after a missed dose. Follow your healthcare provider’s instructions.
What Happens When You Miss Insulin?
When there is not enough insulin available, glucose cannot be used properly by the body’s cells. As a result, glucose can remain in the bloodstream and blood sugar levels may increase.
The effects can vary from person to person. Someone may notice symptoms within a few hours, while another person may not feel any different even though their blood sugar is elevated.
The type of insulin also matters. Different insulin products work for different lengths of time, so missing a long-acting dose can have different effects from missing a mealtime dose.
Common Side Effects of Missing Insulin
One of the most common effects is high blood sugar, also called hyperglycemia.
Signs of high blood sugar can include:
- Increased thirst
- Frequent urination
- Dry mouth
- Tiredness
- Blurred vision
- Headache
- Difficulty concentrating
The severity of these symptoms can vary. Some people may have high blood sugar without noticing obvious symptoms.
If high blood sugar continues, the risk of more serious complications can increase.
Can Missing Insulin Cause High Blood Sugar?
Yes. Missing insulin can cause blood sugar to rise because there may not be enough insulin to help glucose move from the bloodstream into cells.
The effect depends on the dose that was missed and the type of insulin being used. Other factors, such as eating, illness, stress, and physical activity, can also affect blood sugar levels.
Checking blood glucose as recommended by a healthcare professional can help identify when levels are becoming too high.
Can Missing Insulin Cause Ketones?
Yes. When the body does not have enough insulin, it may start breaking down fat for energy. This process produces substances called ketones.
A small amount of ketones can occur in certain situations, but high ketone levels can become dangerous. If ketones continue to build up, they can cause diabetic ketoacidosis.
Missed or incorrect insulin doses are recognized risk factors for developing DKA.
What Is Diabetic Ketoacidosis?
Diabetic ketoacidosis is a serious and potentially life-threatening complication that occurs when the body does not have enough insulin and ketones build up in the blood.
DKA can develop quickly, particularly in people with type 1 diabetes. Missing insulin is one of the situations that can increase the risk.
Symptoms may include:
- Very high blood sugar
- Excessive thirst
- Frequent urination
- Nausea or vomiting
- Stomach pain
- Extreme tiredness
- Fruity-smelling breath
- Rapid or heavy breathing
- Confusion
These symptoms require urgent medical attention because DKA can become life-threatening.
Is Missing One Insulin Dose Dangerous?
It can be, but the risk is not the same for everyone.
The consequences depend on factors such as the type of insulin, the person’s diabetes, the dose that was missed, current blood sugar levels, and whether the person is sick or dehydrated.
For people with type 1 diabetes, interrupted insulin treatment can be particularly dangerous because they can develop DKA when they do not have enough insulin.
For people with type 2 diabetes who use insulin, the effects can vary depending on how much insulin their body still produces and what other diabetes medicines they use.
What Should You Do If You Miss an Insulin Dose?
There is no single correction that is appropriate for everyone.
The safest approach is to follow the missed-dose instructions provided by your healthcare professional or the information supplied with your specific insulin. If you are unsure what to do, contact your doctor, diabetes care team, or pharmacist.
It is important not to guess at a replacement dose. Taking too much insulin can cause dangerously low blood sugar.
The CDC also recommends discussing what to do if you miss a dose with your healthcare team and pharmacist.
Should You Take Extra Insulin After Missing a Dose?
Do not automatically take extra insulin to make up for a missed dose.
The appropriate response depends on the type of insulin and how long ago the dose was missed. Taking additional insulin without considering insulin that may still be active in the body can increase the risk of hypoglycemia.
Insulin stacking, which means taking additional insulin while a previous dose is still active, can cause blood sugar to fall too low.
For this reason, follow the specific instructions given by your healthcare team rather than trying to calculate a replacement dose yourself.
What If Blood Sugar Is High After Missing Insulin?
If your blood sugar is higher than usual after a missed dose, continue monitoring it according to your diabetes care plan.
If your healthcare professional has given you instructions for correction doses, follow those instructions.
Ketone testing may also be important when blood sugar is high, particularly for people with type 1 diabetes or anyone who feels sick. The American Diabetes Association recommends checking ketones in situations such as illness or prolonged high blood glucose.
Do not exercise if you have high blood glucose and ketones unless your healthcare team has specifically told you otherwise.
When Should You Check for Ketones?
Ketone testing can be useful when there is not enough insulin available.
The American Diabetes Association recommends considering ketone testing when blood glucose is around 250 mg/dL or higher for at least two hours, as well as during illness, dehydration, or when you feel unwell. Individual recommendations may differ.
Blood ketone meters and urine ketone strips are commonly used to check ketone levels.
If ketones are elevated, follow the ketone management plan provided by your healthcare team.
When Is a Missed Dose an Emergency?
A missed insulin dose becomes particularly concerning when it is followed by signs of DKA or very high blood sugar.
Seek urgent medical care if you develop symptoms such as repeated vomiting, severe stomach pain, heavy or rapid breathing, confusion, extreme weakness, or fruity-smelling breath.
If ketones are high and getting worse, or you cannot keep fluids down, urgent medical attention is also important.
DKA can worsen quickly and should not be managed by simply waiting for symptoms to pass.
Can Missing Insulin Cause Low Blood Sugar?
Missing insulin itself usually causes blood sugar to rise rather than fall.
However, the situation can become complicated if a person later takes additional insulin to compensate for the missed dose. Taking too much insulin can cause hypoglycemia, or low blood sugar.
Symptoms of low blood sugar can include shaking, sweating, hunger, dizziness, confusion, weakness, and a fast heartbeat. Severe hypoglycemia can cause loss of consciousness, seizures, or coma.
This is why taking an unplanned extra dose to compensate for a missed dose can be risky.
Does Missing Long-Acting Insulin Matter?
Yes. Long-acting insulin provides background insulin over an extended period.
Missing a long-acting dose can lead to rising blood sugar because the body may not have enough background insulin. For people with type 1 diabetes, a significant interruption of insulin can increase the risk of DKA.
Because long-acting and short-acting insulin work differently, the instructions for a missed dose may also be different.
Does Missing Mealtime Insulin Have the Same Effect?
Not necessarily.
Mealtime insulin is generally used to manage the rise in blood sugar associated with food. Missing a mealtime dose can result in higher blood sugar after eating.
The effect depends on the meal, the prescribed insulin, the person’s usual blood sugar levels, and other factors.
The correct action after missing a mealtime dose should come from the person’s prescribed diabetes plan.
How Can You Avoid Missing Insulin Doses?
Simple routines can make missed doses less likely.
Some people find it helpful to:
- Keep insulin supplies in a consistent place.
- Use reminders on a phone or smart device.
- Keep a record of insulin doses.
- Check the dose off after taking it.
- Carry necessary supplies when traveling.
- Ask about smart insulin pens or other tools that can track doses.
Smart insulin pens can record insulin doses and help reduce the chance of skipped doses or accidentally taking another dose too soon.
Frequently Asked Questions
Can missing insulin make you feel tired?
Yes. High blood sugar after missing insulin can cause tiredness, weakness, and a lack of energy.
How quickly can blood sugar rise after missing insulin?
It varies depending on the type of insulin, the missed dose, food intake, and individual blood sugar levels. Some people may notice a rise within several hours.
Can missing insulin cause headaches?
Yes. High blood sugar can sometimes cause headaches, especially when glucose levels remain elevated.
Can missing insulin cause dehydration?
Yes. High blood sugar can cause the body to lose more water through increased urination, which may lead to dehydration.
Can missing insulin cause blurry vision?
Yes. Changes in blood sugar can temporarily affect the shape of the eye’s lens, resulting in blurred vision.
Can missing insulin affect concentration?
Yes. High blood sugar may cause difficulty concentrating, tiredness, or feeling mentally sluggish.
Can stress make the effects of missed insulin worse?
Stress can raise blood sugar levels, so it may make high blood sugar more difficult to control after a missed insulin dose.
Does illness increase the risk of problems after missing insulin?
Yes. Illness can raise blood sugar and increase the body’s need for insulin, making missed doses more concerning.
Can missing insulin cause stomach problems?
High blood sugar and diabetic ketoacidosis can cause symptoms such as nausea, vomiting, and abdominal pain. These symptoms should not be ignored.
Can missing insulin affect sleep?
Yes. High blood sugar can cause increased thirst and frequent urination, which may make it harder to sleep comfortably.
Conclusion
Missing an insulin dose can cause blood sugar to rise, but the effects depend on the type of insulin, the person’s treatment plan, and their individual health.
For people with type 1 diabetes, missing insulin can be especially serious because insufficient insulin can lead to ketone buildup and diabetic ketoacidosis.
The safest response to a missed dose is not to guess or automatically take extra insulin. Follow the instructions provided by your healthcare team for your specific insulin. If you are unsure what to do, contact a doctor, diabetes care team, or pharmacist.
Knowing the warning signs of high blood sugar and DKA can also help people recognize when a missed dose may have become a medical emergency.
Disclaimer – This article is for general informational purposes only and is not a substitute for medical advice. Insulin doses should not be changed or doubled without guidance from a healthcare professional. If you have symptoms of diabetic ketoacidosis or severe blood sugar changes, seek urgent medical care.
