Islets of Hope for persons with diabetes

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Article disclaimer

By Lahle Wolfe


Source: This article contains some excerpts from NIH Publication No. 03–3926, March 2003 that were edited for style and content.

EMedicineHealth: Insulin reactions

When in doubt -- treat for low blood glucose!

If you do not have a glucose monitor on hand and find a diabetic person unconscious -- assume that they are low and administer glucacon -- then call 911.

Did You Know?

Signs and symptoms of hypoglycemia can vary from person to person. Get to know your own signs and describe them to your friends and family so they will be able to help you. If your child has diabetes, tell school staff about hypoglycemia and how to treat it.

If you experience hypoglycemia several times a week, call your health care provider. You may need a change in your treatment plan: less medication or a different medication, a new schedule for your insulin shots or medication, a different meal plan, or a new exercise plan

Medications & Hypoglycemia

Medications, including some used to treat diabetes, are the most common cause of hypoglycemia. Other medications that can cause hypoglycemia include

  • salicylates, including aspirin, when taken in large doses

  • sulfa medicines, which are used to treat infections

  • pentamidine, which treats a very serious kind of pneumonia

  • quinine, which is used to treat malaria

How Often Should You Test Blood Glucose?

Your doctor will advise you as to how often you should test your blood glucose levels to avoid insulin shock or other reasons for hypogly- cemia.  Persons on an insulin pump are usually required to test more frequently.  In general, many care plans call for testing as follows:

Before meals, 2-4 hours after meals, at bedtime, at 3 a.m., and any time you experience signs or symptoms of abnormal blood glucose.

You should test more often when you change medications, when you have unusual stress or illness, or in other unusual circumstances, and, especially when traveling or when driving for long periods of time.

Frequently Asked 
Questions About 
Insulin & Blood
Glucose Monitoring

How often should I check my blood glucose levels?

Any advice or tips for checking blood glucose?

What about "alternative" testing sites?

How do I inject insulin using a syringe or an insulin pen?

What does an insulin pump do?

What is conventional are intensive (flexible) insulin therapies?

How, and when, should I give a glucagon shot? (printable publication)

What is the Dawn Effect? (also called Dawn Phenomenon)

What is the Somogyi Effect? (also called Rebound Hyperglycemia

What are ketones?  How and when should I test for them?

See "Glucose Meters" to learn more about the various types of meters available.

You might also be interested reading about:

Shot Therapy
Insulin Pump Therapy
Insulin Pens
Step-by-Step Guide to Using Insulin Pens
Insulin Delivery Devices


islets of hope diabetes medical library                     back to main "Complications" page
Diabetes Complications

Insulin shock
Risks, causes, treatment, and prevention

Mini Site Index
What is Insulin Shock?
What are Normal Blood Glucose Ranges?
Symptoms of Insulin Shock
The Dangers of Insulin Shock

Bath Time
Brittle Diabetes

For more detailed information and medical alert charts and cards, please read our section on hypoglycemia which includes symptoms, causes, treatment and prevention for all reasons for hypoglycemia.

What is Insulin Shock?

Insulin shock is a term that refers to severe hypoglycemia (low blood glucose).  Some consider it to be a somewhat outdated term, as is the term “insulin reaction”  but it accurately describes the cause of sever hypoglycemia induced when there is too much insulin present, or not enough food eaten for the insulin administered.  Insulin shock can also be applied to induced hypoglycemia caused by reaction from too much oral diabetes medication. 

Different people may have various “normal” ranges of blood glucose that feel comfortable to them, and not everyone experiences symptoms of insulin shock at the same range.  Some people lack total awareness of hypoglycemia (hypoglycemia awareness) and may not even recognize that they are low.  This is particularly true for young children and those that suffer frequent episodes of hypoglycemia.  However, any reading of 50 mg/dL or lower can quickly lead to a situation where a person can lose consciousness, or become confused and disorder to the extent they are unable to care for themselves. 

For the remainder of this text, we will use the terms insulin shock and hypoglycemia interchangeably.

Some of the causes of hypoglycemia:

  • Too much insulin being administered
  • Honeymooning
  • Not enough food
  • Too much exercise
  • Insulin being injected (or bolused with a pump) too close to bedtime, bath time, or exercise (especially when muscles being used during exercise are injected)
  • Hot weather
  • Injecting a normal dose of insulin while on an airplane (see our travel tips section)
  • Basal rates set too high (insulin pump), or
  • Sometimes, from emotional excitement, especially in children.

No matter what the reason for low blood glucose, it is treated in the same manner.:  give fast-acting sugars or glucagon if necessary.

It is important to note that diabetic coma is not necessarily the same thing as insulin shock even though insulin shock can lead to coma.  Insulin shock results from blood glucose levels that are too low and but a diabetic coma can also result from blood glucose levels becoming too high.

See our sections on diabetic ketoacidosis, hypoglycemia, and hyperglycemia for more detailed information.


Normal and Target Blood Glucose Ranges in mg/dL

Time of Day


Your doctor may set different ranges for you. USE THE TARGET RANGES YOUR

Notes for Diabetics Only
Your doctor will give you instructions tailored to your own medical needs.  

Morning (Fasting)


90-130 (adults)
90-140 (children)
Morning highs may be from the Dawn Effect or the Somogyi Effect.
Before Meals



90-130 adults & older children

100-140 children

"Before meals" means 2-4 hours after last meal was eaten.  For those on rapid insulin only (pumps), generally by 2 hours you should be in, or close to, target range.  Those on shot therapy may not be in range until about 4 hours after their last meal.
2-4 Hours After Meals


Less than 180 but high enough that hypoglycemia won't result from any "onboard" insulin if testing at only 1-2 hours.

Pumpers typically come into target range faster than those on shot therapy (assuming both have given the correct amount of insulin).  Ask your doctor when you should test (2 or 4 hours after a meal)

Before Bedtime


Adults, usually 140-160 (after snack)

Children may have a higher pre-bedtime ranges than adults, up to 180

Have a pre-bedtime snack to help avoid nighttime lows. Note: high-fat snacks late in the evening can cause hyperglycemia (high BG) during the night.

(low blood glucose)

70 or lower

70 or lower

Newly diagnosed, and young children often have higher BG target for hypoglycemia (80-100); infants even higher.

Treat hypoglycemia anytime BG is 70 or lower. Newly diagnosed may be instructed to treat at 100. Stable, but young children may be advised to treat at 80-90. Bear in mind that 100 is fine 4 hours after eating but 100 would be too low only 1 hour after insulin.  Be sure to ask your doctor WHEN (how long after insulin) to treat for hypoglycemia and not just by the BG reading alone.
(high blood glucose)
200 or higher may indicate diabetes

Over 180, 2-4 hours after a meal (2-4 for pumpers, 4 hours for those on shot therapy)

Over 140, morning fasting

Test urine for ketones when blood glucose is 240 or higher. Call doctor for care instructions when scheduled BG reading is over 240 more than twice in one day.

BG = blood glucose

(1) People that are newly diagnosed or just beginning a new type of therapy (such as insulin pumping or going from conventional insulin therapy to intensive insulin therapy) may have slightly higher target ranges set for a certain period of time.  This is done to help avoid dangerous episodes of hypoglycemia (low blood glucose) while medication dose or method of delivery is being adjusted.  Be sure to keep in close contact with your physician whenever your diabetes care plan changes.

    For more information about normal and target blood glucose ranges for diagnostic tools for pre-diabetes, diabetes and gestational diabetes (as set forth by the American Diabetes Association), please see "Normoglycemia."


    Symptoms of Insulin Shock

    Symptoms of insulin shock (hypoglycemia) include

    • hunger
    • nervousness and shakiness
    • perspiration
    • dizziness or light-headedness
    • sleepiness
    • confusion
    • difficulty speaking
    • feeling anxious or weak

    Hypoglycemia can also happen while you are sleeping. You might

    • cry out or have nightmares
    • find that your pajamas or sheets are damp from perspiration
    • feel tired, irritable, or confused when you wake up

    The Dangers of Insulin Shock

    Contrary to what some may think about diabetes, sugar does not present the biggest danger to someone with diabetes – insulin and insulin enhancing/sensitizing drugs do.  This is because too much insulin can cause rapid, life-threatening problems, whereas high blood glucose problems usually take hours or even days to present a life-threatening situation (but both hypoglycemia and hyperglycemia should always be addressed immediately).

    A person on shot therapy “feeds” the insulin.  That is, they eat in accordance to how much insulin is given, and when it cycles through the body.  A person on an insulin pump has greater flexibility and no longer has to eat to support the insulin, but can still experience hypoglycemia if basal rates are set too high, or the meal bolus is not calculated correctly.

    The key to remember is that when too much insulin is present, blood glucose levels will drop too low.  This is true for people with type 1 or type 2 diabetes who can suffer from bouts of hypoglycemia.  Anyone with diabetes should check blood glucose regularly and at the first sign or symptom of any blood glucose problem. 

    To help others care for you in the event of a severe hypoglycemia reaction you should:

    • Carry testing supplies, insulin, glucagon, fast-acting sugars, at least one spare set of supplies for insulin pump users,
    • Wear medical alert identification,
    • Keep medical information including a list medications, known drug and environmental allergies, family contacts, and physician information in your wallet, purse and glove compartment.  It is also helpful to emergency personnel if you write down your insulin schedule including amount and time normally given, your correction factor, and insulin-to-carb ratio, and
    • A note that instructs anyone finding you unconscious or disoriented to immediately call 911 or, if possible, administer glucagon, but not to try and force food or drink if you cannot swallow.  

    Treatment for Insulin Shock

    The treatment for insulin shock is the same as for any episode of hypoglycemia.  A person suffering from low blood glucose requires immediate attention; fast acting sugars, and/or glucose or glucagon injection.  Read “Hypoglycemia” for detailed information about symptoms, treatment, and prevention of low blood glucose.  For a printable (illustrated) guide about when and how to inject glucagon, click "Glucagon Publication."

    If you think your blood glucose is too low, use a blood glucose meter to check your level. If it is 70 mg/dL or below, have one of these "quick fix" foods right away to raise your blood glucose:

    • 2 or 3 glucose tablets 1/2 cup (4 ounces) of any fruit juice
    • 1/2 cup (4 ounces) of a regular (not diet) soft drink
    • 1 cup (8 ounces) of milk
    • 5 or 6 pieces of hard candy
    • 1 or 2 teaspoons of sugar or honey

    After 15 minutes, check your blood glucose again to make sure that it is no longer too low. If it is still too low, have another serving. Repeat these steps until your blood glucose is at least 70. Then, if it will be an hour or more before your next meal, have a snack.

    If you take insulin or a diabetes medication that can cause hypoglycemia, always carry one of the quick-fix foods with you. Wearing a medical identification bracelet or necklace is also a good idea. If you ever feel like you might be low but do not have a meter to test your blood glucose levels, treat the symptoms as if you are low with a fast sugar and check your blood glucose as soon as possible.  

    IOH Health Tip:  Your doctor may have provided other care instructions for you.  Be sure that you understand what you are supposed to do to treat low and high blood glucose levels.  If you are unsure, call your doctor.  A good rule of thumb, however, is ... when in doubt -- treat for low blood glucose!

    Exercise can also cause hypoglycemia. Check your blood glucose before you exercise.

    Severe hypoglycemia can cause you to lose consciousness. In these extreme cases when you lose consciousness and cannot eat, glucagon can be injected to quickly raise your blood glucose level. Ask your health care provider if having a glucagon kit at home and at work is appropriate for you. This is particularly important if you have type 1 diabetes. Your family, friends, and co-workers will need to be taught how to give you a glucagon injection in an emergency.

    Prevention of hypoglycemia while you are driving a vehicle is especially important. Checking blood glucose frequently and snacking as needed to keep your blood glucose above 70 mg/dL will help prevent accidents.  


    Preventing Insulin Shock

    One of the most important things you can do to prevent insulin shock is also one of the easiest:  always test your blood glucose BEFORE administering insulin.

    It also helps to keep a journal of diabetes care information because insulin-to-carb ratios and correction factors are not cut in stone and can change from time to time for a variety of reasons.  Be sure to include insulin dose and the time it was given, your blood glucose level, what you ate and when, and exercise.  It is also helpful to note stress, illness, and other medications taken because all of these things can affect blood sugar.

    When you are having trouble managing your blood sugars go over the log with your physician who can determine whether you need less insulin, more food, a different insulin schedule, different type of insulin, or if other factors are causing your episodes of low blood glucose. Without keeping good records of your care, it can be difficult to isolate what is causing episodes of regular hypoglycemia.  

    Bath Time

    One thing I learned the hard way was that you cannot give your child a shot of insulin and put them into the bathtub.  The warm water increases circulation and a dose of insulin can begin to work faster and cause insulin shock.  Talk with your doctor about the timing of baths and insulin shots because how long you have to wait after an injection depends upon the type of insulin(s) you are using.  Some insulin requires you wait almost 4 hours from injection prior to bathing, or bath no sooner than 45 minutes before giving an injection.  

    Brittle Diabetes

    Brittle diabetes is a term used to describe extreme fluctuations in blood glucose due to inaccurately dosing or timing insulin.  Some may mistakenly think that “brittle diabetes” refers to hard to manage diabetes for other reasons; it doesn’t.  It refers to the inaccurate administration of insulin (too much or too little).  Brittle diabetes can result because it is difficult at first to learn how to care for yourself or your child, and things like honeymooning, sick days, and even life events can affect your needs for insulin.

    Your doctor can better help you control brittle diabetes when you keep accurate records detailing your daily diabetes care.


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    Page Updated 03/04/2007