If your doctor suspects diabetes, he or she will recommend
a screening test. Various blood tests can be used to screen
for diabetes, including:
random time. Regardless of when you last ate, a random blood
sugar level of 200 milligrams per deciliter (mg/dL) or higher
suggests diabetes.
overnight fast. A fasting blood sugar level less than 100 mg/dL
is normal. A fasting blood sugar level from 100 to 125 mg/dL
is considered prediabetes, which indicates a high risk of
developing diabetes. If it’s 126 mg/dL or higher on two
separate tests, you’ll be diagnosed with diabetes.
An oral glucose tolerance test may also be performed. For this
test, you fast overnight, and the fasting blood sugar level is
measured. Then, you drink a sugary liquid, and blood sugar
levels are tested periodically for the next several hours. A
reading of more than 200 mg/dL after two hours indicates
diabetes. A reading between 140 and 199 mg/dL indicates
prediabetes.
The American Diabetes Association recommends routine
screening for type 2 diabetes beginning at age 45, especially
if you’re overweight. If the results are normal, repeat the test
every three years. If the results are borderline, ask your doctor
when to come back for another test. Screening is also
recommended for people who are under 45 and overweight if
there are other heart disease or diabetes risk factors present,
such as a sedentary lifestyle, a family history of type 2 diabetes,
a personal history of gestational diabetes or blood pressure above
135/80 millimeters of mercury (mm Hg).
If you’re diagnosed with diabetes, the doctor may do other tests
to distinguish between type 1 and type 2 diabetes — which often
require different treatment strategies because in type 1 diabetes,
the pancreas no longer makes insulin.
After the diagnosis:
Glycosylated hemoglobin (A1C) levels need to be checked between
two and four times a year. This blood test indicates your average
blood sugar level during the past two to three months. Hemoglobin
is the protein that carries oxygen in your red blood cells, and the
A1C test works by measuring the percentage of your hemoglobin
that has blood sugar attached. The higher your blood sugar levels,
the more hemoglobin you’ll have with sugar attached. Your target
A1C goal may vary depending on your age and various other
factors. However, for most people, the American Diabetes
Association recommends an A1C of below 7 percent. Ask your
doctor what your A1C target is.
The American Diabetes Association has recently introduced a
formula that translates the A1C into what’s known as an
estimated average glucose (eAG). The eAG more closely correlates
with daily blood sugar readings. An A1C of 7 percent translates
to an eAG of 154 mg/dL. That would mean that your average
blood sugar levels are around 150 mg/dL.
Compared with repeated daily blood sugar tests, A1C testing
better indicates how well your diabetes treatment plan is working.
An elevated A1C level may signal the need for a change in your
medication or meal plan.
In addition to the A1C test, the doctor will also take blood and
urine samples periodically to check your cholesterol levels,
thyroid function, liver function and kidney function. The doctor
will assess your blood pressure. Regular eye and foot exams also
are important.
