A Guide to Blood Sugar Monitoring

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A Guide to Blood Sugar Monitoring

The muscles, nerves and fat cells in our body use insulin to get energy from the glucose circulating in our blood1. People with diabetes cannot regulate their blood sugar levels, either because their body doesn’t make enough insulin or doesn’t use insulin effectively. In this article, you’ll learn why diabetic blood sugar monitoring is an important part of diabetes management, alongside the benefits of using continuous glucose monitoring.

What is blood sugar monitoring?

Blood sugar monitoring means checking the glucose level in the blood by using a finger prick blood sugar test kit. People with diabetes must monitor their glucose closely and take action to avoid it becoming too high or too low.
Regular blood sugar testing gives people with diabetes the information they need to adjust their diet or medication as necessary to keep their blood glucose within normal parameters. Your doctor or diabetes healthcare specialist will advise you on how often you need to check your blood sugar level and what to do if it is too high or low.
Blood glucose (sugar) is measured in millimoles per litre (mmol/L)) and the recommended target blood sugar ranges for most adults with type 1 or type 2 diabetes. The target blood sugar range should be:
  • Before meals 2: between 4 to 7mmol/L and
  • Two hours after meals 2: less than 10 mmol/L
  • At bedtime 2: between 5 to 8mmol/L.
However, your doctor will advise whether these parameters are suitable for you.
Over time, blood sugar monitoring can help you recognise how diet, exercise and other lifestyle factors affect your blood sugar, so you can take measures to manage your diabetes more effectively.

Why blood sugar monitoring is important

For people living with diabetes, monitoring blood sugar is important for staying healthy. When blood sugar is too low (hypoglycaemia), vital organs, like the brain and heart, can’t function properly3. Consistently high blood sugar (hyperglycaemia) can damage many parts of the body over time, including the heart, nerves, eyes and kidneys4. Extremely low5 or high blood sugars can be life-threatening6.

Blood sugar monitoring vs continuous glucose monitoring: what’s the difference?

Blood sugar monitoring is a catch-all term that refers to any method of testing blood glucose levels.
For many years, the only way to monitor your blood sugar at home was with a finger prick blood sugar checker. In a finger prick test, you prick the end of your finger with a lancet device before testing the blood with a test strip on an electronic blood sugar machine.
However, a different diabetic glucose monitoring method has emerged in recent years: continuous glucose monitoring (CGM). With continuous glucose monitoring, a small glucose sensor sits beneath the skin, continually measuring your glucose level to provide regular, automatic glucose readings that are displayed on a CGM receiver or an app on a compatible smartphone or device. Glucose monitors do not measure blood sugar but instead measure the amount of sugar in the fluid surrounding your cells. This is known as interstitial fluid.

Blood sugar monitoring for type 1 diabetes

In type 1 diabetes, the body cannot make sufficient insulin7, the hormone that manages blood glucose levels. Without insulin, the cells are not able to access the circulating glucose, and blood glucose levels can become too high. Insulin will therefore need to be administered on a daily basis to ensure your blood glucose levels remain at an optimal level.
People with type 1 diabetes should try to check blood glucose levels before meals, two or three hours after eating, before, during and after exercise and before bed. This will help you to understand your blood glucose levels and how they're affected by meals, exercise and sport8. It should also help you to have more stable blood glucose levels.
Managing type 1 diabetes involves closely monitoring blood sugar levels and a careful balance between diet, exercise and insulin dosing. Continuous glucose monitoring (CGM) is beneficial for people with type 1 diabetes, as it replaces frequent finger prick* testing and gives the user a clearer picture of their glucose levels throughout the day and night with 288 readings in 24 hours. CGM systems can even alert users when their glucose falls out of normal range.

Blood sugar monitoring for type 2 diabetes

In type 2 diabetes, the body may be able to produce insulin, but the cells can’t use it effectively. Some people with type 2 diabetes can control blood sugar levels with diet, while others need to take oral medication or insulin9.
Like people with type 1 diabetes, those with type 2 diabetes need to check their blood sugar levels regularly. A continuous glucose monitoring device provides continuous glucose monitoring without the need for frequent finger prick* tests, so the user can easily check their reading at a glance and adjust their diet or medication as necessary.

Is Continuous Glucose Monitoring right for me?

There is a Dexcom CGM system to suit the needs of many different types of diabetes. A Dexcom CGM system will track your glucose levels continuously throughout the day and night. These readings are translated into dynamic data via a compatible smart device, so you're better able to manage your diabetes treatment.
Explore our range of products, including the Dexcom G6 CGM System or our Dexcom ONE CGM System, checker for type 1 - type 2 diabetes, to find the best diabetes CGM system to help you remain active and be supported at all times.
  • Find the Dexcom CGM for You
* If your glucose alerts and readings from the Dexcom system do not match symptoms or expectations, use a blood glucose meter to make diabetes treatment decisions.
† Display devices sold separately. For a list of compatible smart devices, please visit
Tokarz V et al. The cell biology of systemic insulin function. J Cell Biol. 2018 Jul 2;217(7):2273-2289. Available at
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6028526 (Accessed: 01 07 2022)
2 Joslin Education Team. 2022. Goals for Glucose Control. Available at
joslin.org/patient-care/diabetes-education/diabetes-learning-center/goals-glucose-control (Accessed: 01 07 2022)
3 Amie S. The consequences of hypoglycaemia. Diabetologia. 2021 May;64(5):963-970. Available at
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8012317/#!po=5.55556. (Accessed: 01 07 2022)
4 World Health Organization. 2022. Diabetes. Available at
https://www.who.int/health-topics/diabetes (Accessed: 01 07 2022)
5 Endocrine Society. 2022. Severe Hypoglycemia. Available at
https://www.endocrine.org/patient-engagement/endocrine-library/severe-hypoglycemia (Accessed: 01 07 2022)
6 Bell D et al. Hyperglycaemia in the acute care setting. Clinical Medicine Jun 2012, 12 (3) 272-275. Available at
https://www.rcpjournals.org/content/clinmedicine/12/3/272 (Accessed: 01 07 2022)
7 American Diabetes Association. Diagnosis and Classification of Diabetes Mellitus. Diabetes Care. 2004; 27 (suppl_1):s5–s10. Available at
https://diabetesjournals.org/care/article/27/suppl_1/s5/24652/Diagnosis-and-Classification-of-Diabetes-Mellitus (Accessed: 01 07 2022)
8 NHS. 2021. Exercise and Sport. Available at
https://www.nhs.uk/conditions/type-1-diabetes/living-with-type-1-diabetes/exercise-and-sport (Accessed 01 07 2022)
9 Wu Y, et al. Risk Factors Contributing to Type 2 Diabetes and Recent Advances in the Treatment and Prevention. Int J Med Sci. 2014 Sep 6;11(11):1185-200. Available at
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4166864/ (Accessed: 01 07 2022)

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