Monitoring of Blood Glucose


Target Blood Glucose Values

I tell my patients to aim for the following values for their blood glucose.

•Premeal blood glucose should be 70–120 mg/dl, preferably less than 100 mg/dl

•Two-hour after-meal blood glucose should be less than 140 mg/dl, preferably less than 120mg/dl


Frequency of Blood Glucose Testing

If you are a Type 2 diabetic, you should test your blood glucose about two hours after each meal.

However, after a while, this does become cumbersome. Pricking your fingers several times a day is no fun.

I tell my patients to rotate the timing of testing each day. For example, one day check it two hours after breakfast, the next day two hours after lunch, and the third day do it two hours after dinner.

The two-hour after-meal blood glucose value is particularly important for the following reasons.

1- The two-hour after-meal blood glucose is closely linked to the risk for heart attack.

2- It shows the impact of your food on your blood glucose.

The two- hour after-meal blood glucose value should be less than 140 mg/dl, preferably less than 120 mg/dl. A value of more than 140 mg/dl indicates that you either ate too much or you ate the wrong food or a combination of these two factors.

You should write down what you eat. Soon you will know what to eat and what to avoid. Share this diary with your doctor on each visit.

If you are a Type 1 diabetic, then ideally you should check your blood glucose six times a day: before each meal and two hours after each meal.

You check your blood glucose before each meal to calculate the dose of short-acting insulin that you need. The rationale for two-hour after-meal glucose is to see the impact of that particular meal on your blood glucose and also to see if you took enough short-acting insulin to cover that meal. 


Other Tips for Type 1 and Type 2

• Check your blood glucose whenever you are weak, dizzy, or confused

• Record all of these blood glucose values, along with your meal and any symptoms in a log

• Do not forget to bring your log to your appointment with your physician. New glucose meters have the ability to store blood glucose values in their memory.


Hemoglobin A1c (HbA1c)

Hemoglobin A1c (HbA1c) is a blood test that measures overall blood glucose values around the clock for the preceding three months. Therefore, it should be checked every three months.

At the Jamila Diabetes & Endocrine Medical Center, the target goal for my diabetic patients is an HbA1c of less than 6%.

A significant number of patients have been able to achieve this goal. A few even have an HgA1c of less than 5.5%. Patients with an HbA1c of less than 6% rarely suffer from the complications of diabetes.


Seventy-two-hour Continuous Glucose Monitoring

If your diabetes is way out of control or there are wide fluctuations in your blood glucose levels, you may ask your physician to order a seventy-two-hour continuous glucose monitor test.

In this test, you wear a device about the size of a cell phone hooked to a plastic catheter that has a plastic needle at the end. This needle is inserted under your skin by a physician. This device checks your glucose every hour for seventy-two hours (three days and three nights) and can pinpoint the cause of wide fluctuations in your glucose levels. Then your physician can make appropriate adjustments in your medications.

At the Jamila Diabetes & Endocrine Medical Center, I find this test to be extremely useful in difficult cases of diabetes where the cause for wide fluctuations in glucose levels is not apparent or when a patient’s diabetes is severely uncontrolled.


Factors that Can Affect Blood Glucose Values


If you eat a meal that is high in carbohydrates, your blood glucose will go high and it may take a while before you return to normal blood glucose values. 


In Type 2 diabetics, exercise typically lowers blood glucose. Therefore, it’s a good idea to go for a walk after a meal.

However, in some Type 1 diabetics, exercise may initially cause an increase in blood glucose and then a sudden drop. Therefore, Type 1 diabetics should check their blood glucose before exercise. If it is more than 250 mg/dl, then wait for about an hour. Check it again and make sure it’s coming down before you start to exercise. If pre-exercise blood glucose is less than 100 mg/dl, then eat a small snack before exercising.

3- Stress

Both physical and mental stresses can cause an increase in blood glucose.   


Typically, menses can increase your blood glucose. So, monitor your blood glucose more frequently during your menstrual period and adjust the dose of insulin (or insulin stimulating drugs) accordingly.  


Certain medications can influence your blood glucose.

The common ones are:

A. Steroids. Typically, for arthritis, tendonitis, asthma, or a skin disorder, a specialist may treat your condition with a steroid. Many cancer chemotherapy protocols also include steroids. You receive steroids in the form of an injection or pills. Subsequently, you experience a rise in your blood glucose. You wonder what is raising your blood glucose, especially if your specialist did not warn you that your diabetes will get out of control with the addition of steroids.

Knowledge of the connection between steroids and a rise in blood glucose can prepare you to deal with your blood glucose escalating after steroid treatments. You should check your blood glucose more frequently after such treatment and make adjustments in the dose of your diabetes medications in consultation with your endocrinologist.

B. Beta-Blockers. These drugs are typically used in patients with hypertension and heart disease. Common beta-blockers include: atenolol, propranolol, metoprolol, and sotalol. These drugs can worsen insulin resistance and therefore should be used with caution in patients with Type 2 diabetes and insulin resistance.

Beta-blocker drugs can also complicate hypoglycemia. The body responds to hypoglycemia by producing catecholamines that cause symptoms of hypoglycemia, such as sweating and heart pounding. Beta-blocker drugs interfere with the actions of catecholamines and, therefore, can interfere with the symptoms of hypoglycemia. In other words, you may have hypoglycemia and not be aware of it. So beware and discuss this issue with your physician to make sure that the potential benefits of a beta- blocker drug outweigh its potential risks.

C. Birth Control Pills/Hormone Replacement Therapy.

Birth control pills as well as hormone replacement therapy in menopausal women may worsen insulin resistance, which can increase your blood glucose values. So watch your blood glucose closely if you decide to go on birth control pills or hormone replacement therapy.


 I often find my diabetic patients with good control of their diabetes go to the hospital for some acute illness and discover that their diabetes has now soared out of control.

Everyone wonders what happened.

A number of factors are usually responsible for this phenomenon.

• Stress (physical and mental) of the acute illness. Imagine being in the busy ER of a hospital while you wait several hours before someone sees you.

• Intravenous fluids. Almost everyone ends up receiving them while in the hospital. Often they contain glucose.

• Diet. Patients typically receive a diet high in calories as well as high in carbohydrates. Every diabetic patient automatically gets placed on a 1800 Calories diet regardless of the age, or type of diabetes. For most older diabetic patients, these are too many calories.

• Interruption of antidiabetic drugs. Often patients do not receive their antidiabetic drugs while waiting to be seen, waiting for their tests results, or waiting for admission.


This article was written by Sarfraz Zaidi, MD, FACE. Dr. Zaidi specializes in Diabetes, photoEndocrinology and Metabolism.

Dr. Zaidi is a former assistant Clinical Professor of Medicine at UCLA and Director of the Jamila Diabetes and Endocrine Medical Center in Thousand Oaks, California.

Copyright ©  All rights reserved.