Should You Have Your Blood Sugar Checked?

Doctors desk with patients test results
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Obesity is a major risk factor for the development of Type 2 diabetes, so it’s important to know when and how often to have your blood sugar checked to see if you may have diabetes or pre-diabetes.

Blood Sugar Screening

Blood sugar is known as blood glucose in medical terminology, and the U.S. Preventive Services Task Force (USPSTF) released new guidelines regarding blood glucose screening in October 2015.

According to the USPSTF, screening for blood glucose is recommended for overweight or obese adults aged 40 to 70 years. Ideally, this would be done annually as part of the routine health exam and cardiovascular risk assessment.

This recommendation was given with a B rating, and the Affordable Care Act mandates that recommendations with an A or B rating must be covered by health insurance (with few exceptions).

Further, according to the American Diabetes Association’s Standards of Medical Care in Diabetes—2015, the following body mass index (BMI) cut points should be used for identifying those at risk for pre-diabetes and Type 2 diabetes:

  • For Caucasian and African Americans, the BMI cut point is 25 kg/m2 or higher.
  • For Asian Americans, the BMI cut point is 23 kg/m2 or higher.

Additionally, the American Diabetes Association (ADA) recommends considering screening for type 2 diabetes in children and adolescents who are overweight or obese and who have two or more additional risk factors for the development of diabetes.

How Does Obesity Result in Diabetes?

The concept of insulin resistance, in which body organs become resistant to the effects of the insulin that the pancreas does produce, is a very important one in understanding the process that leads to full-blown Type 2 diabetes. Obesity causes insulin resistance, which over time leads to pre-diabetes and then Type 2 diabetes, as the pancreas burns out and simply cannot make any more insulin for a resistant body that has essentially “used up” its insulin stores and production ability.

The metabolic demands of obesity put great stress on the pancreas, which can lead to Type 2 diabetes.

What Is a Normal Blood Glucose Level?

A normal fasting blood glucose level is less than 100 mg/dL. However, many experts recommend keeping a fasting blood glucose level less than 90 mg/dL to steer completely clear of pre-diabetes.

The formal definition of pre-diabetes, representing an increased risk of diabetes, is having a fasting blood glucose of 100 mg/dL to 125 mg/dL or a hemoglobin A1c (a 3-month average measure) in the range of 5.7% to 6.4%, according to the ADA statement. An oral glucose tolerance test (OGTT) may also be used for diagnosis.

For the diagnosis of full-blown diabetes, a number of measures can be used, but for screening purposes, the ones most commonly used are fasting blood glucose or hemoglobin A1c. In those cases, a fasting blood glucose of greater than 125 mg/dL or a hemoglobin A1c of 6.5% or greater makes the diagnosis of diabetes.

The ADA notes that for a fasting blood glucose measurement, “fasting is defined as no caloric intake for at least 8 hours.”


Seaquist ER. Addressing the burden of diabetes. JAMA 2014; 311:2267-68.

Siu AL; U.S. Preventive Services Task Force. Screening for abnormal blood glucose and type 2 diabetes mellitus: U.S. Preventive Services Task Force recommendation statement. Ann Intern Med 2015;163:861-8.

American Diabetes Association. Standards of medical care in diabetes—2015. Diabetes Care 2015;38:S1-S94.

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