How Many Units of Insulin Do I Need for 400 Blood Sugar?

Medically Reviewed on 1/24/2022
How Many Units of Insulin Do I Need for 400 Blood Sugar
To reduce 400 mg/dL blood sugar to about 100 mg/dL, you would need at least 10 units of insulin. However, this depends on your weight and other factors

In a healthy individual, one unit of insulin should cause their blood sugar level to drop 30-50 mg/dL, However, the number of units of insulin needed for people with diabetes depends on factors such as:

  • Type of insulin
  • Site of injection (injection in the abdomen has a better rate of absorption than in the arms or thighs)
  • Insulin resistance
  • Body weight
  • Use of oral diabetes medications
  • Comorbid conditions such as kidney failure, untreated hypothyroidism, or sepsis (pro-inflammatory states) which temporarily increase insulin resistance
  • Time since your last carb-rich meal

Theoretically, to reduce 400 mg/dL blood sugar to about 100 mg/dL, you would need at least 10 units of insulin. However, depending on your weight and other factors, a higher dose of insulin is almost always required.

How are insulin doses calculated?

Insulin may not be given in a single dose. Doctors often calculate insulin doses according to:

  • Basal glucose levels 
  • Fasting glucose levels
  • Postprandial glucose levels 
  • Carbohydrate consumption

A general calculation for a person’s daily insulin requirement is as follows: 

Total daily insulin requirement (in units of insulin) = weight in pounds ÷ 4

Alternatively, if you measure your body weight in kilograms:

Total daily insulin requirement (in units of insulin) = 0.55 × total weight in kilograms

Out of the total dose requirement, 30%-40% should be given as a long-acting or basal dose when you are fasting and between meals, and the remaining 60%-70% is for carbohydrate coverage (food) and high blood sugar correction. This is called bolus insulin replacement.

Since there are different types of insulin and dosage varies according to blood sugar levels, it is important to consult your doctor regarding your insulin prescription and dosage.

What is diabetes?

Diabetes occurs when you are unable to produce or use enough insulin for normal body functions. There are two types of diabetes:

  • Type I diabetes: Autoimmune disease that damages insulin-producing cells in the pancreas and prevents the normal secretion of insulin. Type I diabetes is generally diagnosed in young people. 
  • Type II diabetes: Caused when the body becomes resistant to the effect of insulin and thus requires additional insulin to produce the same effects. This leads the pancreatic cells to produce excess insulin that eventually burns them out. Type II diabetes symptoms can be observed in people of any age.


Diabetes: What Raises and Lowers Your Blood Sugar Level? See Slideshow

What is the role of insulin in the body?

Insulin is a hormone secreted by the beta cells of the pancreas and helps regulate glucose in the bloodstream. 

After eating a meal, carbohydrates break down into glucose, which acts as the primary source of energy for the body. Glucose enters the bloodstream and stimulates the pancreas to make insulin, which allows the glucose to enter the cells and be used for energy production. Excess glucose gets stored in the liver as glycogen. 

When glucose levels decrease in between meals, the stored glycogen is released back into the bloodstream as glucose to maintain optimum glucose levels. 

Insulin acts as a regulator and aids in maintaining glucose levels in the bloodstream by signaling excess glucose to be stored in the liver for future use or producing required glucose when levels drop.

How is insulin therapy used to treat diabetes?

People with type I diabetes require insulin therapy because their body does not produce insulin at all, whereas people with type II diabetes require insulin therapy because their inherent insulin is less effective due to insulin resistance.

Insulin is categorized according to how fast they work and how long their effects can last:

  • Rapid-acting: Produces effects within minutes and lasts for a couple of hours. Examples: lispro and aspart
  • Regular or short-acting: Produces effects within 30 minutes and lasts up to 3-6 hours. Examples: Novolin and Velosulin
  • Intermediate-acting: Can take 2-4 hours to work and can last up to 18 hours. Examples: Neutral Protamine Hagedorn
  • Long-acting or basal: Can work for 24 hours. Examples: degludec, detemir, and lantus
  • Pre-mixed: Examples: Novolog and Humalog mix

Your doctor determines the correct type of insulin to prescribe by considering the following factors:

  • Age
  • Lifestyle
  • Response to a particular type of insulin (time it takes to absorb and its effectiveness
  • Ability to monitor blood sugar throughout the day

How is insulin therapy given?

Insulin can be injected into the bloodstream with the help of a needle and syringe, cartridge system, or through prefilled pen systems. Quick-acting insulin devices and insulin pumps are also available.

Insulin is absorbed most effectively when injected subcutaneously in the abdomen, followed by the buttocks, thighs, and arms.

How are insulin doses scheduled?

It is crucial to follow your doctor’s guidance while scheduling your insulin doses. Doctors may recommend that you use more than one type of insulin depending on your disease progression.

Before understanding the scheduling structure, below are a few terms that are associated with insulin therapy:

  • Onset: Period in which the insulin reaches the bloodstream and begins to act
  • Peak: Period in which the insulin works best
  • Duration: Length of time the insulin continues to work

Doses are scheduled according to the onset, peak, and duration of the type of insulin the person with diabetes uses.

  • Rapid-acting insulin: Taken 15 minutes before mealtime
  • Short-acting insulin: Taken 30-60 minutes before a meal
  • Intermediate-acting insulin: Taken 1 hour before mealtime
  • Pre-mixed insulin: Depends on the product; should be taken 10-45 minutes before mealtime
  • Basal insulin: Taken at night before sleep

Long-acting insulin is taken 1-2 times a day on a flexible schedule. However, in some cases long-acting insulin is combined with shorter-acting insulin or medication.

What is sliding scale insulin therapy?

One of the most controversial therapies for treating diabetes is sliding scale insulin therapy. In this method, blood sugar is measured by a glucometer, taken before meals and at bedtime. The dose of insulin is then administered according to the sugar level.

Governing organizations strictly prohibit the use of this method in healthcare facilities, however, because it has been proven to be ineffective in regulating blood sugar levels accurately.

What to keep in mind when taking insulin

  • Store insulin in a cool, dry area. The ideal room temperature to store injectable insulin should not be higher than 80 F, and it can be kept at that condition for 30 days.
  • Direct sunlight should be avoided.
  • When drawing the insulin out of the bottle, make sure the bottle does not contain any clumps, and avoid shaking to avoid air bubbles. 
  • Eat a balanced diet and exercise regularly to help manage your blood glucose levels.

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Medically Reviewed on 1/24/2022
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