All Health Topics

How and when to change your insulin dose

Nov 5, 2018

You need to learn how to change insulin doses on your own.

Insulin doses need to be raised or lowered:

  • Throughout life as you grow
  • For different activities
  • For foods that may affect your blood sugar differently
  • When you are sick

The information on the following pages may be hard to learn. Learning to change insulin doses can take time. It is important to learn this because changing insulin doses at home when needed and between diabetes appointments will help to control your blood sugar.

It is better to prevent high blood sugars than to chase them with extra insulin at the time of the high. It is better to prevent low blood sugars than to chase them with extra quick-acting carbohydrate.

Your certified diabetes educator (CDE) will teach you how to change your insulin doses to prevent high or low blood sugar. We will help you by phone or email for several months after you find out you have diabetes. After you learn to change insulin doses without our help, we are still here to help you when you need.

Before you learn how to change insulin doses, you will need to:

Know the action of both your long-acting and rapid-acting insulins:

  • When insulin starts to work
  • When insulin peaks
  • When insulin is done working

Learning about when insulin works will help you know which insulin dose to change.

Know your target range for blood sugar.

  • Blood sugar target range before meals: 70 to 150
  • Blood sugar target range at bedtime and during the night: 90 to 150

Try to get half of your blood sugars in the target range. It is okay to have 2 to 4 low blood sugars in a week.

The rest of your blood sugars may be higher than the target range.

Know what causes high blood sugar:

  • Eating too much carbohydrate or too much quick-acting carbohydrate
  • Not enough activity
  • Stress
  • Insulin may need to be increased
  • Forgetting to take insulin
  • Illness or infections
  • Injury or surgery

Know what causes low blood sugar:

  • Taking too much insulin
  • Not eating enough carbohydrate after taking insulin
  • Getting more activity than normal
  • Drinking alcohol

Know that when you check your blood sugar, the number tells us how well your last dose of insulin worked.

For example, meal rapid-acting insulin peaks in 1 to 2 hours and lasts 3 to 4 hours. Your blood sugar taken 2 hours after the meal tells us how well the peak of the insulin covered the peak of the blood sugar after you ate. Your blood sugar taken before the next meal tells us how well the insulin worked during the time your carbohydrate was breaking down.

Know to look down each column on the blood sugar log to see if there is a pattern of high blood sugar or a pattern of low blood sugar.

There are 6 columns:

  • Before breakfast
  • 2 hours after breakfast
  • Before lunch
  • 2 to 3 hours after lunch
  • Before supper
  • 2 to 3 hours after supper before the bedtime snack

Know a pattern of high blood sugar is when blood sugars are over the target range of 150 for 3 days in a row when you look down the column.

To bring high blood sugars down and break the pattern of high blood sugar, your insulin dose that affects that column needs to increase.

Know a pattern of low blood sugar is when blood sugars are lower than the target range of 70 or 80 (based on your age) for 1 to 2 days in a row when you look down the column.

To bring low blood sugars up and break the pattern of low blood sugar, your insulin dose that affects that column needs to decrease. Change your insulin dose if you cannot find another reason for the high or low blood sugars.

Know that when you increase or decrease a dose of insulin, your current insulin dose will change by 10 percent.

Your current insulin dose Column with 1 or 2 blood sugars in a row and no cause for the lows Column with 3 high blood sugars in a row and no cause for the highs
0.5 to 5.5 units Decrease by 0.5 unit Increase by 0.5 unit
6 to 15 units Decrease by 1 unit Increase by 1 unit
16 to 25 units Decrease by 2 units Increase by 2 units
26 to 35 units Decrease by 3 units Increase by 3 units
26 to 45 units Decrease by 4 units Increase by 4 units

Let’s practice changing insulin doses

When you practice, it will help you understand which insulin dose was changed and why it was changed.

Date Night blood sugar Before breakfast blood sugar Insulin carbohydrate After breakfast blood sugar Before lunch blood sugar Insulin Carbohydrate After lunch blood sugar Carbohydrate Before supper blood sugar Insulin Carbohydrate Before bedtime snack blood sugar Long-Acting Insulin Carbohydrate Comments
12/1   148 7   186 121 6   212   136 5.5   96 18    
12/2   268 7   201 94 6   246   82 5.5   122 18    
12/3   255 7   200 117 6   119   149 5.5   149 18    
12/4   196 7   122 90 6   166   252 5.5   120 20    
12/5   114 7   141 89 6   132   112 5.5   192 20    
12/6   111 7   199 142 6   190   92 5.5   213 20    
12/7   124 7   200 113 6   127   122 5.5   186 20    
12/8   118 7   197 107 6   155   104 6   112 20    
12/9   132 7   181 96 6   169   97 6   104 20    
12/10   128 7   164 82 6   172   90 6   91 20    
12/11   116 7   149 66 6   195   160 6   132 20    
12/12   92 7   168 70 6   180   142 6   121 20    
12/13   101 6   179 110 6   215   112 6   101 20    
12/14                                  

Practice 1

Reference the breakfast column on Dec. 2, 3, and 4.

  • These 3 days in a row that show a pattern of high blood sugars over the target blood sugar range of 150.
  • This means the last insulin dose taken, the long-acting insulin from the night before, needs to be increased (go up) by 10 percent.

Next, look at the long-acting insulin dose column at bedtime, on Dec. 4.

  • You will see the long-acting insulin was increased from 18 units up to 20 units. This is a 10 percent change.

Practice 2

Reference the before bedtime column of blood sugars on Dec. 5, 6, and 7.

  • These 3 days in a row show a pattern of high blood sugar over the target blood sugar range of 150.
  • This means the last insulin dose taken, before supper, needs to be increased by 10 percent.

Next, look at the before supper insulin column for the next day, on Dec. 8.

  • You will see the before supper insulin dose was increased from 5.5 units up to 6 units. This is a 10 percent change.

Practice 3

Reference the before lunch column of blood sugars on Dec. 11 and 12.

  • These 2 days in a row show a pattern of low blood sugar less than the target range of 70 to 80 (based on age).
  • This means the last insulin dose taken, before breakfast, needs to be decreased by 10 percent.

Next, reference the before breakfast insulin dose for the next day, on Dec. 13.

  • The before breakfast insulin dose is decreased from 7 units down to 6 units. This is a 10 percent change.