Once the blood sample has been taken, it will be analyzed for glucose (blood sugar) content. The physician can then make a diagnosis about whether or not the patient has diabetes or prediabetes. If so, a treatment plan will be developed to manage the patient’s glucose levels. This usually involves lifestyle changes (exercise, weight loss, diet modification) and may involve medications such as antidiabetic agents or insulin therapy.

The following are blood glucose levels and how they are interpreted by most physicians. All measures in the chart below are in milligrams per deciliter (mg/dL):

With the glucose challenge test, which screens pregnant women for gestational diabetes, results below 140 mg/dL are considered normal. Above-normal results do not always indicate gestational diabetes and will prompt the physician to order an oral glucose tolerance test, which is more complicated but more specific.

In some cases, blood glucose abnormalities may indicate a condition other than diabetes or prediabetes. Other conditions that can cause high blood glucose (hyperglycemia) include:

• Overeating
  
  
• Severe stress
  
  
• Heart attack
  
  
• Stroke

• Cushing’s syndrome (excess production of cortisol hormone)
  
  
• Medications including corticosteroids, aspirin, diuretics, beta blockers (a class of antihypertensives), antidepressants, lithium, epinephrine and estrogens
  
  
• Hyperthyroidism (overproduction of thyroid hormone)
  
  
• Acromegaly (bone and muscle disease involving excess production of growth hormone)
  
  
• Pancreatitis (inflammation of the pancreas)

• Some cancers of the pancreas
  
  
• Pheochromocytoma (noncancerous tumor that can exacerbate high blood pressure)

Low blood glucose (hypoglycemia) can also indicate health problems. Lower-than-normal glucose levels generally considered to be a health threat are:

• Below 40 mg/dL for women
• Below 50 mg/dL for men

Conditions that can cause lower-than-normal blood glucose levels include:

• Addison’s disease (decreased production of adrenal hormone)
  
  
• Hypothyroidism (decreased production of thyroid hormone)
  
  
• Tumor in the pituitary gland or hypopituitarism (decreased production of pituitary hormone)
  
  
• Liver diseases such as cirrhosis
  
  
• Kidney failure

• Malnutrition
  
  
• Medications including acetaminophen
  
  
• Insulinoma (tumor in the pancreas that causes overproduction of insulin)