Insulin Medications for Diabetes

Reviewed on 4/5/2021

What is the diabetes medication insulin and how does it work?

Insulin is a hormone produced by certain cells in the pancreas called beta cells. Insulin helps the body use blood glucose (a type of sugar) for energy. When we eat and absorb food, glucose levels rise and insulin is released.

Some people can't make insulin; those people have type 1 diabetes. A person with type 2 diabetes can make insulin, but the body doesn't respond well to insulin; they have "insulin resistance."

For what conditions is the diabetes medication insulin used?

  • Insulin medication is always necessary for type 1 diabetes because the body has no internal source of insulin.
  • People with type 2 diabetes may also need insulin, particularly those who have difficulty controlling their diabetes with oral medications.

Are there differences among types of insulin?

Insulin medication is always necessary for type 1 diabetes because the body has no internal source of insulin. People with type 2 diabetes may also need insulin, particularly those who have difficulty controlling their diabetes with oral medications.

  • Rapid-acting insulins start working in less than 15 minutes, peak in an hour, and continue working for another two to four hours.
  • Regular, also known as short-acting insulin, takes about 30 minutes to reach the bloodstream. Its peak effect is in about two to three hours, and its effect lingers for three to six hours.
  • Intermediate-acting insulin reaches the bloodstream in two to four hours, peaks in four to 12 hours, and works for up to 18 hours.
  • Long-acting insulin takes six to 10 hours to start working, but it lasts for 20-24 hours.

Many people with diabetes may use different types of insulins to get the optimal effect on their blood sugar levels. Premixed insulins can be a convenient option for some people.


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How is the diabetes drug insulin administered?

Insulin must be injected for most patients, though there is a new inhaled form. Injections are done with a disposable fine needle and syringe or the use of a pump.

People with diabetes generally rotate injection sites to prevent tissue injury and for the best insulin absorption. Insulin is absorbed most quickly when it is injected into the abdomen; the thighs and buttocks are other common injection sites. Some people with diabetes find it more convenient and comfortable to use newer insulin delivery systems, such as prefilled or cartridge pen insulin dispensers. While these eliminate the need to draw up insulin from a bottle, they may limit dosing flexibility. Still others benefit from use of insulin pumps, which deliver a continuous dose over 24 hours through an implanted catheter. Insulin pumps are more commonly used by people with type 1 diabetes.

How should the diabetes medication insulin be stored?

Insulin storage depends on when it will be used. Extra bottles should be kept in the refrigerator until ready for use, when they can be brought to room temperature to make injections more comfortable. Insulin should never be frozen or stored in direct sunlight or where there might be excess heat, such as in a car.

How often should blood glucose be checked when taking insulin?

Just as insulin dosing is a highly individual thing, so are recommendations for frequency of blood glucose testing at home. Doctors may advise testing first thing when you wake up before your first meal, before meals, or after meals. Diabetic people with a history of good relatively stable blood glucose levels might get by with less frequent testing.

Another way doctors monitor glucose control is by checking A1c. The A1c test gives information on the average blood glucose control over the past two to three months.

What are the side effects of the diabetes drug insulin?

The main side effects of insulin have to do with taking too little or too much of the drug. The former can result in high blood sugar or hyperglycemia.

  • A person with diabetes who has hyperglycemia frequently or for long periods of time may suffer damage to the blood vessels, nerves, and organs. In a worst-case scenario, hyperglycemia can lead to
  • Low blood sugar, or hypoglycemia, can result from taking too much insulin, although missing meals and exercising excessively can also bring it on. This, too, can be life-threatening. Initial signs of hypoglycemia include
  • High doses of insulin can lower levels of potassium. If potassium gets too low (hypokalemia), it can cause muscle aches or weakness, abnormal heart rhythms, and even death. Other side effects of insulin include the following:
    • break down of fat at the injection site(the injection site might be depressed or raised)
    • allergic reactions, which can be local or involve the entire body.
    • The latter may be life-threatening.


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What are the drug interactions with the diabetes medication insulin?

Some drugs increase blood sugar levels and the need for insulin. They include:

Other drugs may require a person to use less insulin. These include:

Beta-blocker medications, often used for heart disease, may mask symptoms of hypoglycemia (low blood sugar).

What are warnings and precautions the diabetes drug insulin?

  • Insulin should not be used if low blood sugar is present.
  • Any adjustment of insulin, whether to a different brand, type, strength, or method of administration, must be made under medical supervision.
  • Injury, illness, surgery, pregnancy, and changes in activity level can affect blood sugar levels, which might require an adjustment in insulin dose.
  • Patients should inform medical providers of previous medical history before using insulin, especially adrenal/pituitary gland problems, infections, kidney or liver disease, thyroid issues, and nerve problems such as tingling or numbness.
  • Patients should advise medical providers if they are pregnant.
  • Alcohol can increase the risk of developing low blood sugar.
  • Children and the elderly may be more sensitive to insulin.
  • Discard open vials of insulin after 28 days.
  • Do not use insulin after its expiration date.

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