Carbohydrate Counting,
Using Carbohydrate Insulin Ratios
Level 3
Level 3 is designed for people who take insulin and who have chosen intensive diabetes management, using multiple daily injections (MDI) or an insulin pump.  At levels 1 and 2, you kept food and blood (BG) records to help you understand the relationship between the food you eat, your physical activity and BG levels.  This information is vital at every level of carbohydrate counting.  This is the information you use to fine-tune your diabetes management.
At level 3, this information can be used to adjust short acting (regular) insulin according to the carbohydrate you eat and your physical activity.  The direct relationship between the insulin you take and the food you eat can be shown as a ratio, a carbohydrate-to-insulin ratio.  This ratio will give you a good idea of how much regular insulin to use when you eat more or less than you usually do.
Level 3 Carbohydrate Counting will give you greater flexibility in food choices and portion sizes.  Your intensive insulin regimen will give you greater flexibility in the timing of your meals.  The ultimate goal of Level 3 Carbohydrate Counting is to improve BG control and to prevent or delay long-term diabetes complications.

Who should use carbohydrate/insulin ratios?
 nyone using Level 3 Carbohydrate Counting will have already had in depth diabetes education, have advanced knowledge and skills, and be in close contact with a diabetes health care team.  It is recommended that you also meet the following requirements:
1. Before you can establish a carbohydrate/insulin ratio, your BG levels should be under good control and the basal dose of insulin well adjusted.   Basal insulin refers to your intermediate-acting insulin (NPH, Lente) or long acting insulin if you are on MDI, or the continuous flow of background (regular) insulin if you are on a pump.  Basal insulin mostly covers your nonfood insulin needs, while your bolus doses at mealtime are intended to cover your food needs.  With the insulin pump, the bolus insulin given before the meal can be delivered in amounts as small as one-tenth of a unit.

2. You should have mastered insulin adjustment. This means you have the ability to adjust basic daily doses based on patterns seen in several days of BG records.
3. You should also have mastered insulin supplementation.  This means that you have the ability to alter doses of Regular insulin to promptly correct BG levels outside of your target range.
You should have received individual instructions already from your health-care team on how to adjust insulin based on your BG levels.  Some teams refer to these adjustments as a sliding scale.

How do you develop carbohydrate/ insulin ratios?
You and your dietitian (RD) will develop your carbohydrate /insulin ratio by reviewing at least 2 weeks of records of carbohydrate you have eaten and the number of units of Regular insulin you used to meet your target BG. Ideally, you will try to be consistent with your food and activity for these 2 weeks.
Records of your food, carbohydrate intake, medication, BG, and activity will be as important in level 3 as in level 1 and 2.  You may continue to use a daily record keeping form or you may decide to use a data summary type form, with several days of data on one sheet.  You and your RD should discuss which forms are best for your needs.
When your BG levels consistently fall within target range, you are ready to determine a carbohydrate/ insulin ratio.  If not, your RD and health care team will assist you with pattern management.  Pattern management includes studying interpreting, and taking action based on relationships between food, medication, and physical activity.  The goal of pattern management is improved BG control.
The amount of carbohydrate you eat determines how much insulin you need to cover a meal.  Protein and fat that you eat are absorbed more slowly and have little effect on your BG level.  Your carbohydrate/insulin ratio will cover your usual amounts of protein and fat, as well as your carbohydrate in that meal.
There are several approaches you can take learning your individual carbohydrate/insulin ratios.  Two commonly used methods are described on the following pages.
Carbohydrate Gram Method
The carbohydrate gram method allows you to see the differences in your ratios from one meal to another.  For example some people find their ratio at dinner is different from their ratio at breakfast.  Many people have lower carbohydrate to insulin ratios at breakfast than at dinner.
For example, at breakfast the ratio may be 10/1, while at dinner 1 unit covers 15 grams of carbohydrate.  This happens when early morning hormones affect your sensitivity to insulin, causing high BG (often called the “dawn phenomenon”) and a greater need for insulin in the morning.
Please note that the lower the carbohydrate/insulin ratio, the more insulin you need to cover your food.
Using the carbohydrate gram method to figure your carbohydrate/ insulin ratio is simple if you have met certain criteria. 

  • First, you should be eating a consistent amount of carbohydrate at the meal for which you want to find your ratio.
  • Second your insulin dose for that meal should have been fine tuned so that your pre-meal and post meal BG’s are within your target range.  For example your pre-meal target range may be 3.9-7.2 mmol and your 1 1Û2 -2 hr post-meal target  + or – 2 points but less than 10 mmol.

For the day’s meal divide the number of grams of carbohydrate by the units of Regular insulin.  For example, if you are looking at breakfast and you took 3 units R for 45 grams carbohydrate, your carbohydrate/ insulin ratio is

45 grams carbohydrate  = 15 grams carbohydrate
               3u R                                      1u

This would be a 15/1 ratio.
Now look at the other 2 breakfast meals and see if this 15/1 ratio is also true.  If not, discuss why it is different with your RD and health care team.
Some possible explanations are different at times between taking your insulin and eating or differences in your activity level on those 3 days. 
You may now want to experiment with the ratio you have calculated.  Using the previous example, you might try eating a 60-gram carbohydrate breakfast.
· Divide the total number of grams of carbohydrate by 15 to find the number of units of insulin you’ll need.
60g carbohydrate divided by 15= 4u R
You would take 4 units pre-meal BG in the target range.
· Remember also figure how much more or less insulin you need whenever your BG is not in the target range (your insulin supplement).
For example, you may have been advised to take 1 unit extra Regular insulin for each 2.5 points of BG above your target.   Or you may be asked to subtract insulin from your dose if your BG is below target, based o your personal insulin sliding scale or insulin supplement formula.
A word of warning:  If you do not know how much more (or less) insulin you need when your BG is out of your target range, you will not get the best results possible and could increase your risk of having severe hypoglycemia.  Any experimenting with different doses and different amounts of carbohydrate should be done with the support of a health-care team experienced in intensive insulin therapy and diabetes self management. When you use a carbohydrate/insulin ratio, you first figure your dose based on the amount of carbohydrate that you plan to eat.
Then you add or subtract the amount of insulin needed to bring your BG into the target range.
For example, your pre-meal BG is 11.1.  Your target range is 3.9-7.2.  You plan to eat 60 grams of carbohydrate, and your ratio is 15 grams carbohydrate/1 unit insulin.
60g carbohydrate ) 15 = 4uR (for carbohydrate)
     +1uR (to correct BG)
It will take a total of 5 units to R to cover your carbohydrate and to correct your BG to the target range.

Carbohydrate Choices Method
If you do not count actual grams of carbohydrate but think instead in carbohydrate choices or exchanges, you may prefer the carbohydrate choice methods in which
1 carbohydrate choice = 15 grams carbohydrate.
This method is based on information in the Exchange Lists for Meal Planning.  A worksheet is provided at the back of this guide to help you figure out your carbohydrate to insulin ratio using the carbohydrate choice method.
The ratio is found by dividing the number of units R by the number of carbohydrate choices that insulin dose covers.
If you eat a meal with 6 carbohydrate choices and take 6 units R for a BG in the target range then your ratio would be
6uR ) 6 carbohydrate choices =
1.5 units insulin per carbohydrate choice
Comparison of carbohydrate gram method and carbohydrate choice method.
The carbohydrate gram method offers you more precise insulin adjustments for the grams of carbohydrate that you eat.  To fine-tune your adjustments using this method, it is important to weigh and measure foods, use food label information, and carbohydrate reference books.
Estimating carbohydrate to be eaten on the  Exchange Lists or the carbohydrate choice method is simpler but not as accurate.  See example below.
Insulin adjustment based on this meal.
Carbohydrate Gram method
 If your carbohydrate/insulin ratio is 15 grams of carbohydrate per unit of insulin, you would divide the 90 grams of total carbohydrate by 15 to obtain your meal dose of R.
90 divided by 15 = 6uR
Carbohydrate Choices method
If you take 1 u R per carbohydrate choice, you would take only 5 units using this method:
5 Choices divided by 1 u R = 5uR
This method is simpler but not as precise as the carbohydrate gram method.
Remember!  In addition to determining the amount of insulin required for the meal, you also need to figure the amount of insulin needed to bring your BG into the target range.
Now figure the amount of insulin you would take for this meal using the method you prefer.
1. Carbohydrate Gram Method
Divide the total grams of carbohydrate by your carbohydrate to insulin ratio (grams/unit)
Total g carbohydrate         divided by g/u             =          u R
Carbohydrate Choices Method
Multiply the total number of carbohydrate choices by your ratio (units per carbohydrate choice).
Total carbohydrate choices          x u/carbohydrate
                                                     Choice      =         u R
Then add or subtract any additional insulin based on your BG level and adjust the timing of your injection, if you need to.

 Questions and Answers
Q. How do you use your carbohydrate-to-insulin ratio to figure insulin needed for between meal and bedtime snacks?
A.  Regular insulin peaks (has its maximum effect) usually within 2-3 hours after injection.  If you take insulin for a snack within the peak time of a previous meal injection, you can have overlapping of the injections, which could cause a low BG.  If the snack comes late in the evening, you would be at greater risk for nighttime hypoglycemia.

Your Dietitian and health care team can advise you about these situations.  They may suggest one or more possible actions.
· If you are eating a snack of less than 15g carbohydrate within 2-3 hours of injecting mealtime insulin, you may not need an additional injection.
· If you are planning to eat a snack of 15-30 grams of carbohydrate or more within 2-3 hours of a mealtime insulin injection, you can figure the amount of insulin needed for the snack based on your carbohydrate to insulin ratio.
· The above possible choices will be influenced by your BG at the time of the snack.  If your BG is low, you may be advise to not take the R insulin for the snack.  If your BG is high and it is not bedtime you may be advised to use your usual carbohydrate to insulin ratio to figure the insulin needed for the snack plus supplemental insulin needed for the BG.
· If this snack time occurs close to bedtime and you take NPH or Lente insulin at supper or at bedtime, your team may advise you not to take any extra insulin to cover the snack. Most people who take intermediate acting insulin at bedtime routinely eat at bedtime snack and do not take R insulin at that time.
Q. Can you forget about following your previous meal plan and simply adjust your insulin meal doses based on what you decide to eat each day?
A.  Opinions differ about the answer to this question.  One of the advantages to using carbohydrate to insulin ratios is flexibility with food choices and portion sizes.  However, there is a tendency to gain weight if you consume large amounts of carbohydrate at your meals and snacks and don’t burn off the extra calories you’ve eaten.  Your BG record may look great if you are figuring your insulin needs correctly when you make adjustments for variations in carbohydrate amounts, but you may start to gain weight.
Studies show that following a meal plan consistently is linked with improved BG control overall, which means your body gets to use more of the calories you eat.  Also, be sure you are still eating healthy foods for good nutrition.  Are you including at least 3-5 servings per day of vegetables and 2 fruit servings, as well as a variety of whole-grain breads, cereals, and grains?


Q. Why is your breakfast ratio different from the ratio for lunch and supper?
A. Your basal (background) insulin requirements change throughout the day.  Many people with Type 1 diabetes have higher insulin needs in the earlier morning hours because of the action of certain hormones, this may mean a lower carbohydrate to insulin ratio (more insulin needed to cover food) in the morning compared to later in the day. (For example, a 10/1 ratio at breakfast and a 15/1 ratio at lunch and supper).
People using insulin pumps can program several basal rates, depending on their needs, and may not experience as much change in carbohydrate-to-insulin ratio as people on multiple daily injections.
Check with your health care team regarding the need for possible changes in basal insulin (doses or rates if on a pump). If you all agree that your basal insulin is well adjusted, you simply may need a different carbohydrate to insulin ratio for one or more meals.
Q. Will your carbohydrate to insulin ratio(s) ever change?
A.  If your current carbohydrate to insulin ratio is not helping you meet your target BG levels and you are certain that you are weighing and measuring your portions accurately; you may need to fine-tune your ratio.  If, for example, a 10/1 ratio is producing low BGs that are not accounted for by unusual physical activity, try a 12/1 ratio.
Changes in body weight may change your insulin requirements, so you may need to refigure your ratio when you have weight loss or gain.  Usually weight gain increases your insulin requirements.  Other factors which may change your carbohydrate to insulin ratios include pregnancy, certain medications, and regular exercise.

Q. Is there a maximum dose of insulin that you should not exceed when you are eating unusually large amounts of carbohydrate?
A. Your RD and health care team can help you with setting limits on the occasional splurge that may require unusually large amounts of insulin. You may be advised to avoid foods that require an additional 40-50% of your usual insulin meal dose.   For example, if your usual meal dose is 10 units of insulin, you may be advised to avoid the need for anything over 14-15 units for that meal.  You do not want to increase your risk for hypoglycemia.  Remember also the likelihood of weight gain from all those extra calories.

Q. Should you make insulin adjustments when you eat a high fat meal?
A. If you plan to eat a meal that is much higher in fat than you usually eat, then use your usual carbohydrate to insulin ratio for the pre-meal dose of insulin.  Check your BG 3-4 hours after the meal, as fat is slowly absorbed and may cause a delayed post-meal rise in your BG level.  If your BG is high, add supplemental regular insulin based on guidelines provided by your health care team.


Q. Should you make insulin adjustments when you eat the high fiber meal?
A. For a high-fiber meal, you do not have to make adjustments in your insulin dose.  If the meal you are planning to eat has 5 grams or more of fiber, subtract the grams of fiber from the grams of carbohydrate and use your usual insulin to carbohydrate ratio.


Q.   Should you make insulin adjustments for unusually large portions of meat?
A. If you usually eat 3-4 ounces of lean meat at a meal and you plan to increase that amount to 12 ounces for a special occasion, your usual insulin meal dose may not cover the delayed rise in BG that follows a high protein, high fat meal.  Check this out with your dietitian and healthy care team.
You may need to do one of the following:
· increase your insulin at the meal.
· take your usual amount of insulin, then take additional insulin following the meal, or
· take an insulin supplement 3-5 hours later when the extra protein is being digested and absorbed, and partly converted to glucose.

Q. What about alcohol?  Should you take insulin to cover a beer or glass of wine?
A. Because alcohol tends to lower BG, you generally will not need to take additional insulin for it.  Your own experience may show that mixed drinks containing sugar sweetened beverages or fruit juices or more than 1 or 2 beers may require a small amount of insulin.
Use caution when drinking alcohol.  Be sure that you include a meal or snacks that provide carbohydrate and limit alcoholic beverages to just 1 or 2.  consult your dietitian and health care team about this.

Q. Your carbohydrate to insulin ratio does not seem to be working anymore.  Your BG levels are running higher now.  What can you do about it?
A. First check your weighing, measuring, and food label reading skills to be sure you are figuring correctly the amount of carbohydrate foods that you are trying to match with insulin.
Check with your health care team about the need for changes in your basal insulin.
If this doesn’t help you should consider refiguring you carbohydrate to insulin ratio.
What should you expect from a registered dietitian (RD) to learn level 3 carbohydrate counting?
 At level three, you and your RD will fine-tune your skills in reading patterns in your BG control and developing strategies to meet your target BGs. The RD, with your health care team, provides vital support and encouragement to you.  The RD provide problem solving ideas and additional education as new situations and challenges arise and may suggest other strategies for you to try.  There is no specific time frame for level 3.
Your first visit should include(60-90 minutes):
· discussion of your diabetes management goals,
· assessment of your knowledge and skills for intensive diabetes management,
· assessment of your skill in weighing, measuring, and estimating portion sizes of carbohydrate.
· determination of your readiness to establish your carbohydrate to insulin ratio,
· if not ready, development of diabetes management plan and schedule of follow-up appointments until ready to develop ratio,
· if ready, development of ratio,
· practice with sample meals using carbohydrate/ insulin ratio and making insulin dosage adjustments.
Your second visit should include (45-60 minutes):
·review of your food, activity, insulin, and BG records,
· discussion of your patterns in your BG levels,
· adjustments in carbohydrate/insulin ratios as needed,
· monitoring of weight and other medical outcomes of diabetes nutrition therapy,
· identification of your needs for additional diabetes education,
· appointment for follow-up with health care team, usually quarterly.
Special Considerations
Weight gain. Remember that although extra insulin for extra carbohydrate may work fine, the extra calories may cause weight gain.
Another cause for weight gain may be extra foods used to treat hypoglycemia.  Discuss with your dietitian and diabetes health care team how to prevent low BG episodes and which foods and glucose products are most effective to treat hypoglycemia.
Hypoglycemia.  Taking extra insulin for extra carbohydrate can lead to hypoglycemia.  This is a special concern if you take the extra regular insulin at your evening meal and go to sleep before its action is finished.  Regular insulin may act for 6 hours or longer from the time you take it.
Because of insulin overlap, carbohydrate to insulin ratios should not be used between meals and at bedtime unless you health care team is helping you.
For example, if you use your lunchtime insulin-to-carbohydrate ratio to cover your afternoon snack you may end up taking more insulin when your lunch dose is peaking, and then your snack dose could peak around dinner time, increasing your risk of hypoglycemia.
Good Nutrition.  As your carbohydrate counting skills advance and you enjoy the advantage of more flexible food choices, remember to consider good nutrition.  Be sure to include at least 3-5 vegetable servings and 2 fruit servings in your carbohydrate choices each day.  Also ask your dietitian about your calcium needs.

Practice Worksheet
How to figure your carbohydrate-to-insulin ratio using carbohydrate choices method.
1. Record the regular (R) insulin meal doses that consistently meet target BGs based on your BGs and food records.
Breakfast __________    Lunch _____________ Supper _____________
2. Record the number of carbohydrate choices that you consistently eat at each meal.
Breakfast  ________          Lunch ________       Supper________

3.Determine the units of R insulin per carbohydrate choice for each meal by dividing the number of units by the number of carbohydrate choices.
            units R           =              units per carbohydrate choice
carbohydrate choices
B__________units per carbohydrate choice
L__________units per carbohydrate choice
S__________units per carbohydrate choice
My carbohydrate/insulin ratio is ___________units per carbohydrate choice.

4. If your answers to step 3 are different for one or more meals, use more than one ratio.
My carbohydrate ratios are:
B__________units per carbohydrate choice
L__________units per carbohydrate choice
S__________units per carbohydrate choice
5. To make insulin adjustments for more of fewer carbohydrate choices, add up the total carbohydrate choices  and multiply by your ratio (u/carbohydrate choice).
Total carbohydrate choices _______________
x__________u/carbohydrate choice
=__________u R

Practice Worksheet

How to figure your carbohydrate to insulin ratio using carbohydrate gram method
1. Record the grams (g) carbohydrate that you consistently eat at each meal
Breakfast________g                   Lunch________g              Supper________g
2. Record the regular (R) insulin meal doses that consistently meet target BGs based on your BGs. (u = units of insulin)
Breakfast________u                 Lunch________ u             Supper________u
3. Determine the carbohydrate g per units insulin for each meal by dividing the total g carbohydrate for each meal by the number of u R.
B=Breakfast   L=Lunch    S=Supper
g carbohydrate = ________ g/u
  u R insulin
Breakfast________g/u              Lunch________g/u                      Supper________g/u
4. If your answers to step 3 vary from each other by no more than 1 g carbohydrate, add the 3 answers together and divide by 3 to get the average grams carbohydrate per unit  of insulin.                                                   
    ________ total divided by 3 =________g/u
5. If your answers to step 3 vary from each other by more than 1 g carbohydrate and your health care team agree that your basal insulin doses are well adjusted, then use your answers to step 3 as your carbohydrate to insulin ratios for each meal.
My carbohydrate to insulin ratios are
Breakfast________g/u              Lunch________g/u                      Supper________g/u
6. to make insulin adjustments for more or less carbohydrate eaten, add up the total carbohydrate and divide by the appropriate carbohydrate to insulin ratio.
Total carbohydrate ________g ) g/u (ratio) ________= ________u R