Monday, May 3, 2010

How is Diabetes Diagnosed?

The medical guidelines for diagnosing diabetes is as follows:

Fasting plasma glucose (a blood test after at least 8 hours of fasting):
•80-99 normal
•100-125 pre-diabetes (impaired glucose tolerance)
•126 or over diabetes

2-hour glucose tolerance test (blood test 2 hours after fasting and then drinking 75 grams of glucose):
•under 149 normal
•140-199 pre-diabetes (impaired glucose tolerance)
•over 200 diabetes

Hemoglobin A1C levels:
•under 6.0 normal
•6.0 to 6.4 pre-diabetes
•over 6.5 diabetes

The American Diabetic Association recommends that people aged 45 or older should consider getting tested for pre-diabetes or diabetes. People younger than 45 should consider testing if they are overweight, obese, or extremely obese and have one or more of the following risk factors:
•being physically inactive
•having a parent, brother, or sister with diabetes
•having a family background that is African American, Alaska Native, American Indian, Asian American, Hispanic/Latino, or Pacific Islander
•giving birth to a baby weighing more than 9 pounds or being diagnosed with gestational diabetes
•having high blood pressure—140/90 mmHg or above—or being treated for high blood pressure
•having an HDL, or “good,” cholesterol level below 35 mg/dL or a triglyceride level above 200 mg/dL
•having polycystic ovary syndrome, also called PCOS
•having IFG or IGT on previous testing
•having a condition called acanthosis nigricans, characterized by a dark, velvety rash around the neck or armpits
•having a history of cardiovascular disease—disease affecting the heart and blood vessels

If results of testing are normal, testing should be repeated at least every 3 years. Doctors may recommend more frequent testing depending on initial results and risk status. The ADA states that people whose test results indicate they have pre-diabetes should have their blood glucose checked again in 1 to 2 years and take steps to prevent type 2 diabetes.

I find that many people have a normal fasting blood glucose but still have pre-diabetes. My test of choice for testing for insulin resistence, glucose intolerance and diabetes, which used to be done commonly but is rare now, is a 4-hour Glucose Tolerance Test. The blood glucose level AND the insulin level is taken fasting, and then after a glucose drink it is taken at ½ hour, 1 hour, 2 hours, 3 hours and 4 hours, testing both glucose and insulin levels at each draw. This shows if the glucose and/or insulin goes too high, and often it will then drop too low at 3 or 4 hours, which increases stress on the body. THIS TEST SHOULD NOT BE USED TO DIAGNOSE TYPE 1 DIABETES.

Rather than advocating simply being re-tested in 1 to 2 years if there are any signs of pre-diabetes, we immediately change the diet and other risk factors, and start the patient on supplements that will reduce their risk of getting diabetes.

Type 1 diabetes is diagnosed through the same glucose level parameters. Most children diagnosed with diabetes have type 1, though that is changing. Most diagnoses of type 1 are made when the child presents to the emergency room extremely ill in ketoacidosis.

Most adults diagnosed with diabetes have type 2, but rarely it is type 1. Most of those with type 1 lose weight when their blood sugar rises. Most of those with type 2 fight obesity because of the elevated levels of insulin, which hold onto fat, though this isn't 100% true.

The differences between type 1 and type 2 in testing are:
•People with type 1 have ketones in their urine when their blood sugar is high. People with type 2 don't have ketones, unless they have been fasting or eating only protein.
•Extra testing to determine if diabetes is type 1 include a c-peptide test (which measures levels of this protein associated with insulin production) or tests for islet cell antibodies (ICA), insulin auto-antibodies (IAA), and/or glutamic acid decarboxylase (a beta cell protein known as GAD).

If you suspect the possibility that you may have diabetes or pre-diabetes, please ask your doctor to test you. Early treatment with diet and supplements before medication is needed may keep you from ever needing medication.

The next blog will be on the medications that are used to treat diabetes.

Until we meet again,
Dr. Judi


Karen Ahlstrom said...

My doctor once had me get tested for diabetes when I had some sores on my legs that were obviously infected, but took several courses of increasingly strong antibiotics to clear up. Why would that be?

Dr. Judi said...

People with diabetes tend to get skin infections which may be difficult to heal, especially on the legs. That is probably why he tested you, to see if that would be the reason you weren't healing as easily as is normal.