Blood Glucose Monitoring (T1D)
For people living with type 1 diabetes (T1D), keeping blood glucose within a safe range is the cornerstone of daily management. Monitoring blood glucose levels allows individuals and their healthcare teams to make informed decisions about insulin doses, food choices, exercise, and illness management. Before the development of more advanced technologies such as continuous glucose monitoring (CGM) and hybrid closed-loop systems, self-monitoring of blood glucose (SMBG) was — and remains — the foundation of diabetes care.
Why Blood Glucose Monitoring Matters
Type 1 diabetes results from the autoimmune destruction of pancreatic beta cells, leaving the body unable to produce insulin. Without insulin, glucose accumulates in the blood, leading to acute complications such as diabetic ketoacidosis (DKA) and long-term risks including cardiovascular disease, kidney damage, and vision loss.
Monitoring blood glucose provides immediate feedback, allowing timely correction with insulin or carbohydrate intake. It also informs longer-term treatment planning, helping to set personalised targets and identify patterns such as hypoglycaemia overnight or hyperglycaemia after meals.
Methods of Blood Glucose Monitoring
- Capillary Blood Glucose Testing (Finger-Prick Testing):
Using a lancing device, a person draws a small drop of blood (usually from a fingertip) and applies it to a test strip inserted into a meter. Within seconds, the meter displays the blood glucose value. - Frequency of Testing:
The recommended number of checks varies with age, lifestyle, and clinical circumstances, but most people with T1D perform several tests per day — typically before meals, before bedtime, and during illness, exercise, or suspected hypoglycaemia. - Accuracy and Limitations:
Modern meters are highly reliable but still subject to variation. Proper technique, test strip quality, and environmental factors (temperature, altitude) can all affect results.
Interpreting Blood Glucose Results
Effective self-management is not only about collecting data but acting on it. Key steps include:
- Adjusting insulin doses based on carbohydrate intake, pre-meal glucose, and planned activity.
- Identifying trends such as recurrent highs or lows at the same time each day.
- Collaborating with healthcare professionals to adjust long-term insulin regimens.
Challenges with Finger-Prick Monitoring
While SMBG has transformed diabetes care over the past four decades, it has several drawbacks:
- Pain and inconvenience from multiple finger pricks each day.
- Limited data — readings are snapshots rather than continuous trends.
- Missed glucose excursions — especially overnight or between checks.
These challenges have spurred the development of newer technologies, including continuous glucose monitoring systems.
Looking Ahead: Continuous Glucose Monitoring (CGM)
CGM uses a tiny sensor inserted under the skin to measure interstitial glucose levels every few minutes. This technology provides a far more complete picture of glucose patterns, alerts for highs and lows, and facilitates more proactive diabetes management. In the next article in this series, we’ll explore how CGM works, its benefits, and its limitations — and how it’s reshaping the standard of care for type 1 diabetes.
Blood glucose monitoring remains the bedrock of effective type 1 diabetes management. While finger-prick testing is still essential for many, the field is moving steadily toward continuous and automated systems. Understanding the basics of self-monitoring sets the stage for making the most of the next generation of diabetes technology — from CGM to hybrid closed-loop insulin pump therapy.
Page updated: September 2025
