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Insulin is a hormone produced by your pancreas that helps shuttles sugar from your blood to the tissues in your body. People with type 1 diabetes and advanced type 2 diabetes need to take insulin to regulate their blood sugar levels.

Neutral protamine Hagedorn (NPH) insulin (named after the scientist Hans Christian Hagedorn who invented it) peaks in about 6 to 8 hours, with a duration of up to 12 hours. This type of insulin is generally used to help regulate blood sugar levels between meals and overnight.

This article will take a closer look at how NPH differs from other types of insulin, how long it takes to reach peak effect, and the potential side effects.

Historically, insulin was derived from cows or pigs. But now, animal insulin isn’t as common, thanks to improved technology.

NPH insulin is made from synthetic insulin that’s grown in bacteria or yeasts in a lab. Zinc and a protein extracted from fish (called protamine) are added to slow its absorption in the body.

NPH insulin is approved by the Food and Drug Administration (FDA) and used to treat type 1 and advanced type 2 diabetes in children and adults. It’s the most common type of basal insulin, which is insulin used to keep blood sugar levels constant between meals and overnight.

In the United States, NPH insulin is sold under the brand names Humulin N and Novolin N.

NPH insulin is considered intermediate-acting insulin because it lasts for about half a day. It takes longer to act than the natural insulin in your body. NPH is often mixed with regular or rapid-acting insulin to combine the benefits.

NPH insulin is administered subcutaneously into the layer of fat under your skin using a pen or syringe into your abdomen, arms, or thigh.

Many types of insulin can treat diabetes, and your doctor can help you decide which type is best for you.

Types of insulin

Insulin is typically divided into one of four types depending on how long it takes to act:

  • Rapid-acting. Starts to act within 15 minutes. Peaks in about 1 hour. Usually taken right before a meal.
  • Regular or short-acting. Onset is around 30 minutes. Peaks in about 2 to 3 hours. Usually taken about 30 to 60 minutes before a meal.
  • Intermediate-acting. Starts to act in 1 to 2 hours. Peak time is 6 to 8 hours. Used to keep blood sugar levels constant for about half a day or overnight.
  • Long-acting or ultra-long acting. Starts to act within 1 to 2 hours. Does not peak, but duration is typically 24 to 36 hours.
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NPH insulin generally acts within 1 to 3 hours and has a peak time of about 6 to 8 hours.

Peak time is the period when a medication has its strongest effect. It varies based on the type and brand of insulin you use. It’s essential to know the peak time of your insulin so that you can predict how much and when you should eat to keep your blood sugar constant.

NPH insulin can last for up to 12 hours and is typically injected once or twice per day. It can last longer than 12 hours in people with certain medical conditions like kidney failure.

When you inject NPH insulin into the subcutaneous layer of your skin, the insulin spreads through your fat tissue and connective tissue until it reaches small blood vessels called capillaries. Various factors can affect how long it takes for the insulin to reach your bloodstream and start acting. These include:

  • injection depth
  • thickness of your fat tissue
  • temperature of your fat tissue
  • your level of activity and exercise
  • the part of your body injected
  • whether you’re a smoker
  • body position during the injection

All types of insulin come with a risk of side effects. These include:

NPH insulin has a slightly higher risk of causing low blood sugar than other types of insulin. Severe low blood sugar can cause symptoms like seizures, loss of consciousness, or death.

Mild cases of hypoglycemia can cause symptoms like:

People with kidney or liver conditions are at a higher risk of developing severe low blood sugar. It’s important to talk with your doctor if you develop side effects so that your doctor can help you adjust your insulin dose.

Before taking NPH insulin, it’s important to talk with your doctor about the pros and cons of this type of insulin and to get clear instructions on:

  • when you need to use it
  • how often you need to take it
  • how much you need to take each time
  • how to administer it
  • where to inject it

To ensure that you’re administering NPH insulin safely and effectively, it’s also essential to take the following steps:

  • Tell your doctor about any known allergies before starting insulin therapy.
  • Provide your doctor with information on all the medications and supplements you’re taking before starting insulin therapy.
  • Let your doctor know if you start taking a new medication or supplement.
  • Alert your doctor if you develop health issues that may affect insulin absorption. This includes hormonal changes, diarrhea, vomiting, or conditions that delay stomach emptying.
  • Wash your hands with soap and water before injecting yourself with insulin.
  • Confirm that you have the correct type and strength of insulin prescribed to you by your doctor before administering it.
  • Check that your insulin isn’t expired.
  • Carefully follow the instructions on the insulin label.
  • If your insulin is cloudy, mix it by gently rolling it between your fingers.
  • Avoid using insulin if it looks unusual. Instead, contact your pharmacist or doctor for advice.

It’s critical to never share insulin syringes, pens, or pumps with other people due to the risk of spreading blood diseases like HIV and hepatitis.

NPH insulin is an intermediate-acting insulin that helps keep your blood sugar stable between meals or overnight. It generally starts to act within 1 to 3 hours and has a peak time of about 6 to 8 hours.

NPH insulin is FDA-approved to treat adults or children with type 1 or advanced type 2 diabetes and is often combined with quicker-acting types of insulin.

If you have diabetes, it’s essential to talk with your doctor about the best type of insulin for you. There are many types of insulin, but factors like the severity of your diabetes, other health conditions, and your lifestyle habits can influence which type of insulin is best for you.