Is my insulin to CHO ratio correct?

After you eat your blood glucose may rise a little but if your insulin to carbohydrate ratio is correct then the rise should be small and it should return back to a similar level before your next meal. You should expect a rise of 2-3 mmol two hours after eating

Because your body’s sensitivities to insulin may be different at different times of the day, some people find that they need different ratios for different mealtimes.

There are other factors that can affect your blood glucose so don’t make any changes to your normal ratio based on one abnormal reading. Keep a diary of your insulin dose, carbohydrate eaten and blood glucose readings for a few days to see if there is a pattern. If there is, then make a change and monitor to see if things have improved. You can download a diary by clicking here.

How to test your insulin to carbohydrate ratio

If you want to test whether you are giving the correct bolus dose for the carbohydrate in your meals, then try following these steps:

• Test your blood glucose level before your meal. You should not have given any bolus insulin in the 4 hours before this meal.

• Make sure you have correctly counted the carbohydrate value of your meal.

• Give your usual insulin to carbohydrate bolus.

• Check your blood glucose 2 and 4 hours after your meal.

• If your blood glucose levels have significantly changed from your pre-meal level, review your insulin to carbohydrate ratio.
  • Rising blood glucose after meals suggests you need more insulin/a change in ratio e.g. a 1:10 ratio may need to go to 1:9, or 1:8, for example.

• If at any stage your blood glucose drops below 4 mmol/L, then stop and follow your normal hypo treatment.
  • Regular hypos after meals suggest you need less mealtime insulin/a change in ratio e.g. a 1:10 ratio may need to go to 1:12, for example.

• Speak to your diabetes team about how much you should adjust your ratio to improve your blood glucose levels.

Note: This test should not be done on a day that you are unwell, stressed or had a
hypo in the last 6—12 hours, or when you have done more exercise than usual.