Blood testing for diabetics
Reading Time: 4 minutes

Expert-reviewed by Ashwini S.Kanade, Registered Dietician and Certified Diabetes Educator with 17 years of experience
Fact-checked by Aditya Nar, B.Pharm, MSc. Public Health and Health Economics

Watching your diet, exercising regularly and taking medicines on time are not the only essential aspects of your diabetes management plan. Regularly checking your blood sugar levels should also be a priority if you have diabetes. You have to know your blood sugar levels to manage it, isn’t it?

But how often should you check it? Do you need to self-monitor in between your lab-tests? We break down everything you need to know about blood sugar monitoring for people with diabetes.

The basics

The glucose levels in your blood vary throughout the day. It is lowest in the morning before you consume any food, rises for 1-2 hours after you eat and then goes back down if you are non-diabetic But if you have diabetes, the levels may continue to be elevated.

Do I need to regularly check my sugar levels if I am diabetic?

Yes, especially if you have type 2 diabetes and are using insulin.

How does regular checking help?

Regular checking shows how your diet, stress, exercise and insulin is affecting your blood sugar and this can help you modify your lifestyle better. Helps reduce your chances of developing long-term complications.[1]

The effectiveness of your glucose control management can be assessed by self-monitoring of blood glucose (SMBG) and A1C blood test. Continuous glucose monitoring (CGM) can play a role too.

What are the different ways to monitor blood sugar levels?

Blood sugar can be tested in the following ways:

  1. Self-monitoring
  • Traditional home monitoring with glucometers – you use the blood collected from capillaries (tiny blood vessel within the tissues) through a finger prick.
  • Continuous glucose monitoring – measures the sugar levels throughout the day in your body’s tissue every few minutes.
  1. Lab tests Lab tests use a sample of blood extracted from your veins.
  • Fasting blood sugar (FBS) – Usually done first thing in the morning after an overnight fast
  • Random blood sugar (RBS) – blood samples are taken at any random time of the day
  • Post-prandial blood sugar (PPBS) – measures blood glucose 2 hours after eating a meal
  • HbA1c – evaluates average level of blood glucose over the previous three months

Are self-monitoring and continuous monitoring effective?

Self-monitoring of blood glucose has been associated with better sugar control in patients with insulin-treated type 2 diabetes. But there is no convincing evidence to support its use in people with moderately well-controlled type 2 diabetes who are not using insulin.[2,3] CGM can improve quality of blood sugar control, reduce the risk of low blood sugar (hypoglycaemia) and lower A1C.[4]

How often should I check my blood sugar levels?

The frequency and timing of checking blood sugar levels vary from individual to individual. Your doctor may recommend how often you should check your blood sugar levels depending on the type and severity of your condition as well as your specific needs and goals.

Most patients using insulin regimens will require testing their blood glucose levels 6–10 (or more) times daily. The recommendations of American Diabetes Association for self-monitoring of blood glucose are as follows:[5]

Patients on intensive insulin regimens
  • before meals and snacks
  • at bedtime
  • occasionally post-prandial (after meals)
  • before exercise
  • when low blood glucose suspected
  • after treating low blood glucose until normal levels are achieved
  • before critical tasks such as driving
Type 2-diabetics on a less intensive insulin therapy
  • fasting
  • before meals
  • after meals
Monitoring in pregnant women with diabetes
  • fasting
  • postprandial (after meals) monitoring – associated with better sugar control and lower risk of preeclampsia (high blood pressure that occurs during pregnancy)
  • preprandial (before meals) testing – recommended for women with pre-existing diabetes using insulin pumps


Nocturnal hypoglycemia (low blood glucose at night) is common if you are on insulin therapy. According to Ashwini Kanade, Registered Dietician and Certified Diabetes Educator, 3 AM blood sugar check is essential for such patients.

How often should you get lab tests done?

You may need lab tests periodically in conjunction with self-monitoring to monitor your glucose control over time. The glycosylated haemoglobin (HbA1c) lab test aids in monitoring the long-term control of your blood sugar. The recommendations for A1C testing are:[5]

  • If your blood sugar control is good – at least two times a year
  • If your blood sugar control is poor – four times a year

Lab tests VS self-monitoring – what is better?

There is a small but significant disparity between the two measured values. Glucometers are less precise. Their readings are approximately 10% higher than the lab readings. But they are fast and convenient to use. They also have the level of accuracy needed in the routine care of diabetes. They can be used safely and effectively to dose your insulin. But they may not be appropriate for hospital use.[6]

Photo courtesy: Pixabay


[1] Martin S, Schneider B, Heinemann L, Lodwig V, Kurth HJ, Kolb H, Scherbaum WA. Self-monitoring of blood glucose in type 2 diabetes and long-term outcome: an epidemiological cohort study. Diabetologia. 2006 Feb;49(2):271-8. Epub 2005 Dec 17. PubMed PMID: 6362814.

[2] Schütt M, Kern W, Krause U, Busch P, Dapp A, Grziwotz R, Mayer I, Rosenbauer J, Wagner C, Zimmermann A, Kerner W, Holl RW; DPV Initiative. Is the frequency of self-monitoring of blood glucose related to long-term metabolic control? Multicenter analysis including 24,500 patients from 191 centers in Germany and Austria. Exp Clin Endocrinol Diabetes. 2006 Jul;114(7):384-8. PubMed PMID: 16915542.

[3]  Malanda UL, Welschen LM, Riphagen II, Dekker JM, Nijpels G, Bot SD. Self-monitoring of blood glucose in patients with type 2 diabetes mellitus who are not using insulin. Cochrane Database Syst Rev. 2012 Jan 18;1:CD005060. doi: 10.1002/14651858.CD005060.pub3. Review. PubMed PMID: 22258959.

4] Rodbard D. Continuous Glucose Monitoring: A Review of Recent Studies Demonstrating Improved Glycemic Outcomes. Diabetes Technol Ther. 2017 Jun;19(S3):S25-S37. doi: 10.1089/dia.2017.0035. PubMed PMID: 28585879; PubMed Central PMCID: PMC5467105.

[5] [American Diabetes Association (ADA) 2017 Guidelines

[6] Scott MG, Bruns DE, Boyd JC, Sacks DB. Tight glucose control in the intensive care unit: are glucose meters up to the task? Clin Chem. 2009 Jan;55(1):18-20. doi: 10.1373/clinchem.2008.117291. Epub 2008 Nov 21. PubMed PMID: 19028817.

Loved this article? Don't forget to share it!

Disclaimer: The information provided in this article is for patient awareness only. This has been written by qualified experts and scientifically validated by them. Wellthy or it’s partners/subsidiaries shall not be responsible for the content provided by these experts. This article is not a replacement for a doctor’s advice. Please always check with your doctor before trying anything suggested on this article/website.


  1. […] What is diabetes but monitoring of blood sugar levels to make sure they stay as close to the normal range as possible. A glucometer with a small memory to record past few readings can only do so much. Using a sound diabetes care app to log and track your blood sugar levels will give you more than a cursory insight into the trends of your diabetes. You will be able to see how your blood sugar levels change before and after a meal, or before and after your meds, and even before and after exercise. Here’s how often experts say you should check your blood sugar levels. […]

Comments are closed.