Manage your diabetes with confidence.

When it comes to diabetes, knowledge is power. Explore the topics below to stay informed and help better manage your diabetes.

What is A1C? 

A1C is a measurement of your average glucose levels over the past two to three months. It’s used by healthcare professionals to measure how well your diabetes is being managed and is given as a percentage.1

The goal for most people with type 1 or type 2 diabetes is an A1C below 7%.2

What’s a normal blood sugar level? 

Recommended blood sugar levels for most people with diabetes3

This table provides general recommendations on blood sugar targets and may not be the same as the targets your healthcare team has set for you. Your targets should be personalized to you.


7.0% or under

Fasting blood glucose (sugar)/blood glucose before meals

4.0-7.0 mmol/L



Blood glucose (sugar) two hours after eating (mmol/L)

5.0-10.0 mmol/L
(5.0-8.0 mmol/L if A1C targets are not being met)



Doctors also use different blood sugar tests to diagnose diabetes. In addition to A1C, doctors will do a Fasting Blood Sugar Test (measures blood sugar levels after an overnight fast) and a Glucose Tolerance Test (measures blood sugar levels before and after drinking a sugary liquid).4

Diabetes is diagnosed when:4

  • A1C is 6.5% or above

  • Blood sugar level is 7 mmol/L or higher after fasting

  • Blood sugar level is 11.1 mmol/L or higher after a glucose tolerance test

Prediabetes is diagnosed when:4

  • A1C is 6.0-6.4%

  • Blood sugar level is 6.1-6.9 mmol/L after fasting

  • Blood sugar level is 7.8-11.0 mmol/L after a glucose tolerance test

A1C Test
Fasting Blood Sugar Test
Glucose Tolerance Test

6.5% or higher

7 mmol/L or higher

11.1 mmol/L or higher



6.1-6.9 mmol/L

7.8-11.0 mmol/L


Under 5.7%

Under 5.5 mmol/L

Under 7.8 mmol/L


How A1C is measured

When glucose is in your bloodstream, it enters your red blood cells and attaches to a protein called “hemoglobin”. A1C is a measurement of the percentage of hemoglobin in your blood that’s attached to glucose.6

A1C and glucose variability 

Whatever your A1C, it’s possible to spend a significant amount of time outside of your target glucose range. Your target glucose range is where you and your diabetes care team would like your glucose levels to be.7  This is why Time in Range should be considered in addition to your A1C.

Consider the following example. These three people all have an A1C of 7%. Person A has spent 100% of the time in their target glucose range while persons B and C have not. Persons B and C have a good A1C, but they’re experiencing glucose variability.

Person A

Person B

Person C

Orange color

Above Target Range (hyperglycemia)

Green color

In Target Range

Red color

Below Target Range (hypoglycemia)

For illustrative purposes only. Not actual patient data.

The Triangle of Diabetes Care

The Triangle of Diabetes Care is an approach to managing your diabetes that goes beyond simply lowering your A1C. Although A1C is an important indicator of your glucose control, research suggests that we should also look at other factors for a better picture of glycemic control.8

By targeting each of the three goals of the Triangle of Diabetes Care, you can help make improvements to your wellbeing as well as your long-term health.9 The main three goals are:

  1. Improve your A1C, in line with your personal goals
  2. Reduce or limit the swings between low and high glucose levels (also called “glucose variability”)
  3. Avoid hypoglycemia (low glucose)

Achieving all three of these goals leads to better diabetes management.8,9

The Triangle of Diabetes Care was developed by Dr. Ramzi Ajjan, Associate Professor and
Consultant in Diabetes and Endocrinology at the University of Leeds.

Tips for using your FreeStyle Libre or FreeStyle Libre 2 system to help achieve these three goals

1. Better manage overall glucose levels (A1C)

Frequent glucose testing helps you to keep an accurate record of your glucose levels. Real-world evidence has also shown that checking your glucose more frequently is associated with reduced estimated A1C.10

2. Limit glucose variability

The FreeStyle Libre and FreeStyle Libre 2 systems allow you to see upward or downward trends using the Trend Arrows, and the Daily Patterns report can show you where you have the most variability in your glucose readings from day to day. If you start to see that your glucose runs low or high at specific times of the day, or in response to particular activities, these can be identified so you can make changes in the future.

3. Minimize hypoglycemia

The Low Glucose Events report on your FreeStyle Libre 2 app* lets you see when and how often your glucose is low throughout a typical day, so you can try and reduce the risk of another hypoglycemic event.

Understanding Time in Range

What is it, and what does it mean?

Time in Range refers to the amount of time each day that you spend within your target glucose range. 

When setting up your FreeStyle Libre or FreeStyle Libre 2 system for the first time, you need to enter the upper and lower values for the Target Glucose Range in the Settings in the FreeStyle Libre 2 app,* with your healthcare professional’s guidance.

Time in Range is another way of talking about Time in Target, which is one of the reports available on the FreeStyle Libre 2 app.* The more time you spend in your target range, the better. 

Time Below Range and Time Above Range are also important measures. The Time in Target report on the FreeStyle Libre 2 app* will show you the percentage of time you’re spending below target range, above target range, and within target range.

In the example below, the Time in Target report shows that this person has spent 22% of the time above target range, 75% of the time within target range, and 3% of the time below target range.

This person has spent 75% of the time in target range

Dark Orange color

6% Glucose is high

Orange color

16% Above target range

Green color

75% Within target range

Red color

3% Glucose is low

Product images are for illustrative purposes only. The examples provided are not intended to be a substitute for professional medical advice. Please consult your physician or qualified health provider regarding your condition and appropriate diabetes plan. Individual symptoms, situations and circumstances may vary.

Expert medical opinion indicates that a target glucose range of 3.9-10 mmol/L should be used to assess Time in Range for most adults with type 1 or type 2 diabetes who are not pregnant, older or considered high-risk.11 Consult with your healthcare team to set target range values that are right for you.

Increased Time in Range can mean fewer diabetes complications

Information from a major clinical trial in people with type 1 diabetes has shown that spending more Time in Range can help to avoid harmful diabetes complications. People in the trial who developed problems with their kidneys or their eyes spent 10-12% less Time in Range on average than those who did not.12

A different study on people with type 2 diabetes showed that vision-threatening diabetic retinopathy (a type of eye condition) was most common in people who spent the least amount of time in their target glucose range, regardless of A1C level.13

More Time in Range



Lower risk of eye and kidney problems

How much time do you need to spend “in range”?

An international group of diabetes experts has recommended that spending at least 70% of your time (~17 hours/day) in range is advisable for most adults with type 1 or type 2 diabetes who are not pregnant, older or considered high-risk.11

Of course, not everyone will be able to meet this target, or at least not right away. Making improvements in Time in Range will vary for each person with diabetes, and that’s okay. Keep in mind that even small increases in Time in Range can have a positive impact.11  So don’t get discouraged - keep checking your glucose regularly and sticking with your diabetes management plan!


Recommended targets for Time in Range, Time Below Range and Time Above Range for most adults with type 1 and type 2 diabetes who are not pregnant, older or considered high-risk11

Time in Range

3.9-10 mmol/L

- No action needed

More than 70% 
(More than 16 h, 48 min per day)

Time Below Range – Level 1 hypoglycemia

<3.9 mmol/L

- Action needed if symptoms occur or if extended duration


Under 4%
(Under 1 h per day)

Time Below Range – Level 2 hypoglycemia

<3.0 mmol/L

- Immediate action needed


Under 1%
(Under 15 min per day)

Time Above Range – Level 1 hyperglycemia

>10 mmol/L

- Low priority for immediate action


Under 25%
(Under 6 h per day)

Time Above Range – Level 2 hyperglycemia

>13.9 mmol/L

- Immediate action needed to avoid unwanted effects of hyperglycemia (e.g., diabetic ketoacidosis)


Under 5%
(Under 1 h, 12 min per day)


A closer look at hypoglycemia

Why is hypoglycemia important?


Our brains rely on glucose, so if glucose levels drop a lot, it can start to affect brain function.14

There are two categories of hypoglycemia:15

  • Mild or moderate, which can likely be self-treated

  • Severe, which can, in certain instances, require help from another person for recovery

Recognizing hypoglycemia when it happens

Common symptoms of hypoglycemia include:15









Mood swings

Vision changes

Trouble concentrating


Difficulty with speech

When do you start feeling symptoms of hypoglycemia?

In general, people will start to experience symptoms of hypoglycemia when their glucose level is under 4.0 mmol/L. When glucose levels fall below 2.8 mmol/L, a person can lose consciousness and will need the assistance of another person.16

How does hypoglycemia affect our mood and emotions?

Hypoglycemia can make us feel more than just irritable. It can also make us angry and irrational, and in some cases (as with recurrent hypoglycemia) can even lead to anxiety.17

Hypoglycemia can:17

Provoke tense-tiredness (a feeling of being both tense and tired at the same time) and feelings of unhappiness

Increase irritability and anger

Make us pessimistic about everyday situations and about life issues

Lead to mood changes, which are negative, stressful and unpleasant

Lead to anxiety (with repeated episodes of hypoglycemia)

What does cognitive (mental) impairment look like?

Studies have shown that mental function can be affected when glucose levels fall below 3.0 mmol/L. Below this level, people with diabetes may start to experience problems with:14

  • Fine motor coordination

  • Mental speed

  • Concentration

  • Certain memory functions (e.g., word recall, working memory)

Uncommon but serious consequences of hypoglycemia


Coma, seizures, mental impairment, psychological effects14


Falls, accidents, dislocations, driving mishaps14


Angina (a type of chest pain), abnormal heart rhythms, heart failure14,18

Causes and risk factors for hypoglycemia

Causes19 (can lead to hypoglycemia)

  • Insufficient food or missed meals (most common cause)

  • Taking too much insulin or sulfonylurea medication

  • Alcohol consumption (especially if you haven’t eaten)

  • Physical exercise

  • Delayed emptying of the stomach  

Risk factors20,21 (can make hypoglycemia more likely)

  • Increasing age

  • Duration of type 1 diabetes

  • Duration of treatment with insulin in people with type 2 diabetes

  • Previous episodes of severe hypoglycemia (most powerful predictor of future episodes)

  • Impaired awareness of hypoglycemia

  • Kidney disease

  • Decreased mental ability (e.g., depression)

  • Strict control of blood glucose

  • Increased glucose variability

How is hypoglycemia treated?

Non-severe hypoglycemia can be self-treated. If you have symptoms of hypoglycemia and your glucose level is less than 3.9 mmol/L, follow these steps:

  • Eat or drink 15-20 grams of a fast-acting carbohydrate, such as:

    • 4 glucose tablets; or
    • 1 tube of glucose gel; or
    • ½ cup (4 ounces) of fruit juice (NOT low-calorie or reduced-sugar juice) – apple, grape and cranberry juices are good options; or
    • ½ can (4-6 ounces) of pop (NOT diet or reduced sugar); or
    • 1 tablespoon of sugar, honey or corn syrup
  • Check your glucose level again after 15 minutes. If your level is still low, eat or drink another 15-20 grams of a fast-acting carbohydrate, as mentioned above.

  • Continue to check your glucose levels every 15 minutes. Repeat the steps above until your glucose levels are back to normal.  

  • If your next meal is over an hour away, have a healthy snack, like crackers or a piece of fruit.15,21

Severe hypoglycemia has to be treated by other people. The best way to treat severe hypoglycemia is with glucagon - a hormone that raises your glucose levels. Glucagon is available as a nasal spray and injection, and can quickly bring your glucose levels back up. Teach your family, friends and coworkers when and how to give you glucagon. Tell them to call 911 right away after giving you glucagon or if you don’t have a glucagon emergency kit with you.21

Helpful tips for managing hypoglycemia

Tips to prevent hypoglycemia during exercise:22

  • Follow an eating plan, including carbohydrate counting

  • Monitor glucose before and after exercise

  • Eat a snack before exercise if glucose level is low or falling

  • Modify physical activity that’s caused hypoglycemia in the past

  • Take care with prolonged or unaccustomed exercise

  • Watch out for delayed hypoglycemia (several hours after exercise)

Advice for insulin-treated drivers:23

  • Test glucose before driving and during long journeys (every 2 hours)

  • Have a snack before driving if glucose is <5.0 mmol/L; do not drive if <4.0 mmol/L

  • Take regular meals/snacks and take a rest period during journeys

  • Keep an emergency supply of fast-acting carbohydrate in your car AND an additional supply of food

  • Stop the car in an appropriate location if hypoglycemia happens

  • Delay restarting driving until 45 minutes after glucose has returned to normal

Using Trend Arrows on your FreeStyle Libre or FreeStyle Libre 2 system to help you avoid hypoglycemia

The Trend Arrows on your glucose reading can be used to estimate the direction your glucose is heading.



Glucose is rising


Slower rate of change
(0.06-0.1 mmol/L/minute)

Straight Upward

Faster rate of change
(more than 0.1 mmol/L/minute)

Glucose is falling


Slower rate of change
(0.06-0.1 mmol/L/minute)

Straight Downward

Faster rate of change
(more 0.1 mmol/L/minute)

These arrows are especially useful to know if your glucose is lowering and you might be heading towards a hypo (hypoglycemia).

If you see a downward angled Trend Arrow, you know that your glucose is falling. Knowing this, along with your current reading, you can estimate if this is going to take you into the hypoglycemia zone (below 4.0 mmol/L) and take action to bring your glucose back to target as your healthcare team advised you.

Example: Your glucose reading is 4.4 mmol/L and you have a falling Trend Arrow.


Important note:
Keep in mind that the arrow tilted downwards indicates that your glucose is falling at a slower rate (0.06-0.1 mmol/L per minute), whereas the arrow pointing straight down indicates that your glucose is falling at a faster rate (more than 0.1 mmol/L per minute).

Let’s say that you want to estimate where your glucose level will be in 15 minutes. We know that your glucose is changing at a rate of somewhere between 0.06 mmol/L per minute and 0.1 mmol/L per minute. So, what we’re calculating is a range. We need to determine both the lower and upper end of this range to see where your blood glucose could be in 15 minutes. Follow these steps:

  • Use the following calculation to estimate how much your glucose level will change over 15 minutes:

    [rate of change] x [number of minutes since reading] = [change in glucose level (mmol/L)]

    • 0.06 mmol/L/minute x 15 minutes = 0.9 mmol/L
    • 0.1 mmol/L /minute x 15 minutes = 1.5 mmol/L
  • Next, you will SUBTRACT these values from your current glucose reading. This will give you an estimate of your glucose level 15 minutes from now.

    [current glucose level] - [change in glucose level] = [estimated glucose level]

    • 4.4 mmol/L - 0.9 mmol/L = 3.6 mmol/L (upper end of glucose)
    • 4.4 mmol/L - 1.5 mmol/L = 3.0 mmol/L (lower end of glucose)

So, in this example, your estimated glucose level in 15 minutes will be between 3.6 mmol/L and 3.0 mmol/L. In this instance, it’s really important to take action right away to stop yourself from having a hypo.

Note: If your glucose is rising and you want to calculate where your glucose level would be in 15 minutes, follow the same steps above. However, in step 2, you will ADD the values to your current glucose reading. So, you would use the following calculation:

[current glucose level] + [change in glucose level] = [estimated glucose level]

IMPORTANT: There are many factors influencing your glucose levels, so although this is handy to know, it’s important to understand that this is only for guidance. Plus, if math just isn’t your thing and you really want to know your glucose reading at any point in time, you can always just re-check your glucose.

Take advantage of the Low Glucose Events report on your FreeStyle Libre/FreeStyle Libre 2 system

The “Low Glucose Events” report from the FreeStyle Libre and FreeStyle Libre 2 systems are a good way to see if any particular part of your day is contributing to episodes of hypoglycemia (hypos). It puts you in the know, so you can make changes to reduce or even avoid hypos.

The FreeStyle Libre and FreeStyle Libre 2 systems record a Low Glucose Event whenever your glucose has fallen below 3.9 mmol/L for more than 15 minutes. The bar graph displays the low glucose events that happened during different periods of the day - overnight, morning, afternoon or evening.

  • If you are using the FreeStyle Libre 2 system, remember that you can set a “low glucose alarm” on your app.* This will alert you day and night when your glucose level passes the value you have set, even before you experience hypoglycemia.

Results that matter

Studies have shown that FreeStyle Libre users spend less time below 3.9 mmol/L than people who use finger prick blood glucose testing.24,25 This important improvement is not just during the day, but also at night when many people may worry about having a hypo.

Be prepared for your next visit with your healthcare professional!

Learn how you can use reports from the FreeStyle Libre or FreeStyle Libre 2 system to have a more productive conversation with your doctor.

Sensor is water-resistant in up to 1 metre (3 feet) of water. Do not immerse longer than 30 minutes. Not to be used above 10,000 feet.

* The FreeStyle Libre 2 app and the FreeStyle Libre 2 reader have similar but not identical features. Finger pricks are required if glucose readings and alarms do not match symptoms or expectations. The FreeStyle Libre 2 sensor communicates with the FreeStyle Libre 2 reader that started it or the FreeStyle Libre 2 app that started it. The FreeStyle Libre 2 app is only compatible with certain mobile devices and operating systems. Please check the Compatibility Guide (PDF 69 kB) for more information about device compatibility before using the app. Use of FreeStyle Libre 2 may require registration with LibreView.

† Finger pricks are required if glucose readings and alarms do not match symptoms or expectations. 



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  2. Imran A, et al. 2018 clinical practice guidelines: targets for glycemic control. Can J Diabetes 2018;42(Suppl 1):S42-S46.
  3. Diabetes Canada. Managing Your Blood Sugar. Diabetes Canada website. September 29, 2022.
  4. Punthakee Z, et al. Chapter 3: Definition, classification and diagnosis of diabetes, prediabetes and metabolic syndrome. Can J Diabetes 2018;42(Suppl 1):S10-S15.
  5. Centers for Disease Control and Prevention (CDC). Diabetes Tests. CDC website. Accessed July 11, 2023.
  6. American Diabetes Association. A1C and eAG. American Diabetes Association website. Accessed December 7, 2022.
  7. Dunn T, et al. Development of the likelihood of low glucose (LLG) algorithm for evaluating risk of hypoglycemia: a new approach for using continuous glucose data to guide therapeutic decision making. J Diabetes Sci Technol 2014;8(4):720-730.
  8. Ajjan R, et al. Glucokinase MODY and implications for treatment goals of common forms of diabetes. Curr Diab Rep 2014;14(12):559-65.
  9. Rayman G. Glycaemic control, glucose variability and the triangle of diabetes care. Br J Diabetes 2016;16(Suppl 1):S3-S6.
  10. Lang J, et al. Expanded real-world use reaffirms strong correlation between scanning frequency of flash glucose monitoring and glucose control. Diabetes 2018;68(Suppl 1):972-P.
  11. Battelino T, et al. Clinical targets for continuous glucose monitoring data interpretation: recommendations from the international consensus on time in range. Diabetes Care 2019;42(8):1593-1603.
  12. Beck RW, et al. Validation of Time in Range as an outcome measure for diabetes clinical trials. Diabetes Care 2019;42(3): 400-405.
  13. Lu J, et al. Association of time in range, as assessed by continuous glucose monitoring, with diabetes retinopathy in type 2 diabetes. Diabetes Care 2018;41(11):2370-2376.
  14. Frier BM, Heller SR, and McCrimmon R, eds. Hypoglycaemia in Clinical Diabetes. 3rd ed. Wiley Blackwell; 2014.
  15. Diabetes Canada. Mild, Moderate or Severe Hypoglycemia - What’s the Difference? Diabetes Canada website. Accessed September 14, 2022.,-moderate-or-severe-hypoglycemia---what-s-the-difference-.
  16. Yale J-F, et al. 2018 clinical practice guidelines: hypoglycemia. Can J Diabetes 2018;42(Suppl 1):S104-S108.
  17. Gold AE, et al. Hypoglycemia and non-cognitive aspects of psychological function in insulin-dependent (type 1) diabetes mellitus (IDDM). Diabet Med 1997;14(2):111-118.;2-S.
  18. Rana O, et al. Acute hypoglycemia decreases myocardial blood flow reserve in patients with type 1 diabetes mellitus and in healthy humans. Circulation 2011;124(14):1548-56.
  19. Kedia N. Treatment of severe diabetic hypoglycemia with glucagon: an underutilized therapeutic approach. Diabetes Metab Syndr Obes 2011;4:337-346.
  20. Frier BM. Hypoglycaemia in diabetes mellitus: epidemiology and clinical implications. Nat Rev Endocrinol 2014;10(12): 711-722.
  21. National Institute of Diabetes and Digestive and Kidney Diseases (NIDDKD). Low Blood Glucose (Hypoglycemia). NIDDKD website. Accessed September 14, 2022.
  22. Seaquist ER, et al. Hypoglycemia and diabetes: a report of a workgroup of the American Diabetes Association and the Endocrine Society. Diabetes Care 2013;36(5):1384-1395.
  23. Inkster B, Frier BM. Diabetes and Driving. Diabetes Obesity Metab 2013;15(9):775-783.
  24. Bolinder J, et al. Novel glucose-sensing technology and hypoglycemia in type 1 diabetes: a multicentre, non-masked, randomised controlled trial. Lancet 2016;388(10057):2254-2263.
  25. Haak T, et al. Flash glucose-sensing technology as a replacement for blood glucose monitoring for the management of insulin-treated type 2 diabetes: a multicenter, open-label randomized controlled trial. Diabetes Ther 2017;8(1):55-73.



The FreeStyle Libre 2 flash glucose monitoring system is indicated for measuring interstitial fluid glucose levels in people aged 4 years and older with diabetes mellitus. Always read and follow the label/insert.
The FreeStyle Libre flash glucose monitoring system is indicated for measuring interstitial fluid glucose levels in adults aged 18 years and older with diabetes mellitus. Always read and follow the label/insert.