What Is NPH Insulin?

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  • Written By: Jacquelyn Gilchrist
  • Edited By: O. Wallace
  • Last Modified Date: 26 October 2019
  • Copyright Protected:
    Conjecture Corporation
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Neutral protamine Hagedorn (NPH) insulin, also called insulin isophane, is a medication used to treat diabetes. It is a synthetic form of a hormone that the body naturally produces in order to regulate levels of glucose, or sugar, in the bloodstream. NPH insulin does this by helping the body's cells use the glucose more efficiently. Diabetics should use a diabetes drug as part of a comprehensive treatment program that includes a physician-approved diet and exercise plan.

NPH insulin begins to work shortly after injection, and it is most effective four to 12 hours after a dose. The effects of the insulin linger for about 18 to 26 hours. A doctor will likely advise the patient to inject the drug 30 to 60 minutes prior to a meal. This diabetes medication is available in prefilled syringes or in vials. Patients should use alternating injection sites that include the upper arm, thigh, and abdomen.


Diabetics should be aware of potential complications of their disease and the insulin. Hypoglycemia, or very low blood sugar, may occur if the patient fasts or uses too much insulin. This condition is typically indicated by shakiness, dizziness, and a rapid heartbeat, as well as feeling faint or anxious. Patients should consume a fast-acting source of glucose, such as glucose gel, to raise blood sugar levels. Hyperglycemia, or very high levels of blood sugar, may cause excessive thirst, fatigue, and a fruity odor on the breath, and it requires a doctor's care.

Some side effects may occur from the use of NPH insulin, which should be reported to the prescribing physician if they become severe. Patients may experience pain, swelling, and redness at the injection sites. More serious side effects require urgent medical care, such as labored breathing, loss of consciousness, and slurred speech, as well as a rapid heartbeat and weakness. Unusual hunger or mood swings may occur, along with vision changes, confusion, and seizures. Rarely, some people may experience an allergic reaction, which could be indicated by facial swelling, tightness in the chest, or muscle pain.

Before using NPH insulin to treat diabetes, patients must disclose their other medical conditions, medications, and supplements. Women who are pregnant or breastfeeding should discuss this with their physicians. Patients should also inform their doctors if they have kidney problems, if they smoke cigarettes, or if they regularly consume alcohol. NPH insulin may interact with other drugs, including corticosteroids, beta-blockers, and angiotensin-converting enzyme (ACE) inhibitors. Certain antibiotics, other diabetes drugs, and diuretics may also interact with NPH insulin.



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