Normal glucose levels in non-diabetic people
Normal glucose levels are between 3.5 and 7.0 mmol/L. Typically, glucose levels are between 3.0 and 5.5 mmol/L on waking, and range between 3.5 – 6.7 mmol/L during the day. They can rise up to a peak of 7.8 mmol/L after eating a serve of carbohydrate, but glucose levels return to normal range within 2 hours.
Ideal glucose levels in diabetes
Keeping glucose levels under control improves your patients’ day-to-day wellbeing. This benefit needs to be balanced against the risk of hypoglycaemia.
If your goal is to prevent cardiovascular disease, lowering your patient’s blood pressure and cholesterol is even more important than glucose management.
How to test glucose levels
The following steps will help your patient test their glucose levels successfully:
When to check the glucose levels
Checking the glucose levels will give and your patient valuable information about how food affects their glucose levels and whether the medications are working.
Your patient wants to learn about how food affects the glucose levels
Your patient is reluctant to check their glucose levels frequently
Your patient refuses to check glucose levels regularly
You are concerned that your patient may be experiencing hypoglycemic episodes Eg. night sweats, chest pain or night mares
How to interpret the glucose levels
When you check glucose levels, you are testing how well the insulin doses match the carbohydrate that is eaten and how much glucose the liver is making. To better understand this, it is good to remember the physiological insulin profile:
Normally, the pancreas secretes a background rate of insulin all day long.
When food is eaten, it secretes a quick surge of insulin that is matched to the amount of carbohydrate and protein that was contained in that meal:
In people with type 1 diabetes, the insulin is deficient.
The mismatch between the normal insulin profile and the actual amount of insulin secreted leads to high glucose levels:
The pre-meal glucose levels reflect how well the basal insulin dose matches the glucose being produced by the liver during fasting and in between meals (hepatic gluconeogenesis). If the pre-meal glucose level is high, it means the dose of basal insulin is too low.
When you check the glucose levels before breakfast, you are testing if the basal dose is right:
The glucose levels after a meal reflects how well the dose of rapid-acting insulin matched the carbohydrate that was just eaten. If the insulin dose was sufficient, the glucose level will be similar to the one checked before the meal. High post-meal glucose levels indicate that the dose was insufficient to meet the required dose for the carbohydrate and, to a lesser extent, the protein in that meal.
Post-meal glucose level (1 – 2 hours after eating):
Glucose level is 5 – 10 mmol/L & stable (less than 3 mmol/L difference between the pre- and post-meal glucose levels)
Post-meal glucose level (1 – 2 hours after eating):
Glucose level is 5 – 10 mmol/L But has dropped more than 3 mmol/L compared with the pre-meal level
Post-meal glucose level (1 – 2 hours after eating):
Glucose is high Above 10 mmol/L and stable (less than 3 mmol/L difference between the pre- and post-meal glucose levels)
Post-meal glucose level (1 – 2 hours after eating):
Glucose is high Above 10 mmol/L and is rising Glucose has jumped more than 3 mmol/L higher than the pre-meal level
Post-meal glucose level (1 – 2 hours after eating):
Glucose is low Less than 5 mmol/L Glucose has dropped more than 3 mmol/L lower than the pre-meal level
The post-meal glucose level tells you about the rapid insulin dose - how well did it match the meal that was just eaten?:
High post-meal glucose levels are seen when:
If you are worried that your patient is having hypoglycaemic events overnight, check the glucose level at 2 – 3am. When the glucose level is checked after midnight, the only insulin working is the basal insulin.
So, if the glucose levels are out of range, this insulin needs to be adjusted:
Testing the glucose level at 2 - 3am is a check for hyperglycaemia. It tells you whether the basal insulin dose is too much: