Short-Acting Insulin

What is short-acting insulin?

Short-acting insulins or regular insulins are recombinant human insulins that were developed to mimic normal after-meal insulin release. They are intended to be used as a bolus mealtime insulin to quickly lower the increase in blood glucose (sugar) after eating. Even though they are regular human insulins, they do not end up controlling the after-meal blood glucose like the insulin produced in the body. This is because after regular human insulin is injected it has a delay before it is absorbed into the body. This delays the onset (usually 30 minutes) and prolongs the effect (usually 3-6 hours) of the injected regular insulin. This limits short-acting insulins effectiveness in providing good glucose control and increases the risk of hypoglycemia.

Some of the short-acting insulins available in the US include:

What is Humulin R (regular human insulin)?

Humulin R (regular human insulin) is used with diet and exercise to improve blood glucose control after meals in the treatment of type 2 diabetes. Humulin R is given as a subcutaneous (under the skin) injection 30 minutes before meals.  It can be injected in the abdomen, thigh, or upper arm or buttocks. Injection sites should be rotated each time to prevent the risk of lipodystrophy, an accumulation of fatty tissue under the skin at the site where  insulin  is injected. Consult with your healthcare provider on proper use and to determine the specific dose needed.

Humulin R is available in a vial containing 100 units/ml (Humulin R U-100), a highly concentrated vial containing 500 units/ml (Humulin R U-500), and a highly concentrated pen containing 500 units/ml (Humulin R U-500 Kwikpen). Humulin R U-500 vials must be injected with a U-500 insulin syringe, otherwise life-threatening hypoglycemia may result. Unopened vials and pens should be kept in the refrigerator. Opened Humulin R U-100 vials should be discarded 31 days after opening. Opened Humulin R U-500 vials can be stored at room temperature for up to 40 days. Opened Humulin R U-500 KwikPens should be stored at room temperature after opening and discarded after 28 days.

Some of the most common side effects from Humulin R  include:

  • Hypoglycemia
  • Injection site reactions
  • Weight gain

Some side effects, like anaphylaxis, hypoglycemia, edema, heart failure or diabetic ketoacidosis can be severe and even life threatening.  Consult your healthcare provider on how to recognize the signs and symptoms of these side effects and let them know if you experience any side effects after using Humulin-R or any other medication.  People who are allergic to any of the ingredients in Humulin R should not use it. Always check with your healthcare professional about any potential drug interactions before starting treatment.   

What is Novolin R (regular human insulin)?

Novolin R (regular human insulin) is used with diet and exercise to improve blood glucose control after meals in the treatment of type 2 diabetes. Novolin R is given as a subcutaneous (under the skin) injection 30 minutes before meals.  It can be injected in the abdomen, thigh, or upper arm or buttocks. Injection sites should be rotated each time to prevent the risk of lipodystrophy, an accumulation of fatty tissue under the skin at the site where  insulin  is injected. Consult with your healthcare provider on proper use and to determine the specific dose needed.

Novolin R is available in a vial containing 100 units/ml. Store unopened vials in the refrigerator. Opened vials should be stored at room temperature for up to 42 days.

Some of the most common side effects from Novolin R include:

Some side effects, like anaphylaxis, hypoglycemia, edema, heart failure or diabetic ketoacidosis can be severe and even life threatening. Consult your healthcare provider on how to recognize the signs and symptoms of these side effects and let them know if you experience any side effects after using Novolin R or any other medication. People who are allergic to any of the ingredients in Novolin R should not use it. Always check with your healthcare professional about any potential drug interactions before starting treatment.  

Written by: Bridget Barvian | Last reviewed: April 2017
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