Managing diabetes involves more than just making dietary changes and taking medication on time. Many individuals with diabetes are also advised to regularly measure their blood sugar levels. However, measuring blood sugar at the wrong times can hinder healthcare teams from accurately assessing the condition or determining whether blood sugar management goals are being achieved.
In this blog post, we’ll guide you through the optimal times to measure your blood sugar, the significance of these readings, and the target blood sugar levels for different times of the day.
Table of Content
Fasting Blood Sugar / Morning Blood Sugar: Timing and Significance
Fasting blood sugar, also known as “morning blood sugar,” refers to the first blood sugar reading taken immediately after waking up.
It is usually taken after at least an eight-hour gap since the previous meal. Measuring fasting blood sugar helps individuals with diabetes evaluate the effectiveness of their medication from the night before.
If fasting blood sugar is too high, it may indicate that the current treatment regimen is not fully effective. Conversely, if it’s too low, it might suggest that the medication dosage is too high or that food intake the night before was insufficient.
- Target fasting blood sugar levels for people with diabetes: 80 – 130 mg/dL (4.4 – 7.2 mmo/L)
Pre-Meal / Preprandial Blood Sugar: Timing and Significance
Pre-meal blood sugar, also known as preprandial blood sugar, refers to the blood sugar level measured before eating. It is usually taken after at least a four-hour gap since the previous meal.
If pre-meal blood sugar is too high, it may suggest that the content of the previous meal needs to be adjusted. However, if pre-meal blood sugar levels gradually increase throughout the day, it could indicate insufficient basal insulin. In such cases, it is important to discuss medication adjustments with your healthcare team.
- Target pre-meal blood sugar levels for people with diabetes: 80 – 130 mg/dL (4.4 – 7.2 mmol/L)
Post-Meal Blood Sugar / Postprandial Blood Sugar: Timing and Significance
Post-meal blood sugar, also known as postprandial blood sugar, refers to the blood sugar level measured two hours after the first bite of a meal.
The primary purpose of this measurement is to understand how food and medication affect blood sugar levels. If post-meal blood sugar is too high, it may indicate overeating or insufficient medication dosage. If it is too low, it suggests that the food intake and medication were not properly balanced.
- Target post-meal blood sugar levels for people with diabetes: 80 – 160 mg/dL (4.4 – 8.9 mmol/L)
Paired Testing: Timing and Significance
Paired testing involves measuring the difference between the pre-meal and post-meal blood sugar levels for the same meal to observe whether adjustments to diet or medication are needed.
If the difference between pre-meal and post-meal blood sugar is too large, it is recommended to review whether the meal contained too many carbohydrates or excessive refined and processed foods. If the diet seems appropriate, it is important to consult with your doctor to see if medication adjustments are necessary.
- Target paired blood sugar difference: 30 – 50 mg/dL (1.7 – 2.8 mmol/L)
Blood Sugar Before Bed: Timing and Significance
Monitoring blood sugar before bed helps determine if it’s necessary to consume an appropriate amount of sugar to prevent nighttime hypoglycemia.
The reading can also be compared with the following morning’s fasting blood sugar to check for the dawn phenomenon.
- Target blood sugar before bed: 90 – 150 mg/dL (5.0 – 8.3 mmol/L)
Blood Sugar at Night: Timing and Significance
Blood sugar at night, or midnight blood sugar, refers to the blood sugar level measured between 3:00 and 4:00 AM.
If fasting blood sugar in the morning is too high, it’s important to measure blood sugar at night to determine the cause of morning hyperglycemia.
- Target blood sugar at night: 80 – 130 mg/dL (4.4 – 7.2 mmol/L)
Timing and Frequency of Blood Sugar Testing for Diabetes
After understanding the significance of different testing times and values, individuals with diabetes can begin planning their own blood sugar testing plan. You can start by setting your blood sugar goals based on your health condition and then create a feasible blood sugar monitoring plan based on your medication regimen:
1. Only Using Oral Medication
You can measure the difference between pre-meal and post-meal blood sugar levels for the same meal, or measure the pre-meal blood sugar levels between two adjacent meals to understand the effect of food on blood sugar.
As for how often to test, you can determine it based on your HbA1c value. If HbA1c is greater than 7%, daily testing is recommended. If HbA1c is smaller than 7%, you can do paired blood sugar testing 2-3 times a week
2. Injecting Long-acting Insulin Before Bed and Using Oral Medication
You can start by measuring fasting blood sugar for 2-3 days to determine if the bedtime insulin dose needs adjustment. Additionally, perform paired blood sugar testing for any meal to make sure that you are not overlooking other episodes of hyperglycemia.
3. Injecting Insulin Twice a Day
Since blood sugar levels need to be checked before insulin injections, you can measure paired blood sugar levels in the morning and evening. This will help you understand the effect of food on blood sugar and make adjustments to your medication.
4. Injecting Insulin 3-4 Times a Day
With more frequent insulin injections, it’s important to check your blood sugar before meals and before bed. This will help you determine if your medication dosage needs adjustment.
Increase Blood Sugar Testing Frequency When Needed
Daily life factors like stress, illness, or emotional fluctuations can impact blood sugar levels. Pay attention to your body and increase testing frequency when needed to better manage your health, such as:
- When feeling unwell
- During periods of significant stress
- After lifestyle or routine changes
- During pregnancy
- When experiencing greater blood sugar fluctuations
Testing + Logging = Smarter Diabetes Management
We’ve shared general blood sugar target suggestions for most individuals with diabetes. If you have other chronic conditions, such as hypertension or cardiovascular disease, be sure to consult your healthcare team to set personalized goals.
Accurate testing is key to managing diabetes effectively. Knowing when to measure and why your blood sugar levels change makes all the difference.
Don’t forget to log your results in Health2Sync! This makes it easy to review past readings and helps your healthcare team provide tailored recommendations for your needs.
