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Screening for Cystic Fibrosis Related Diabetes (CFRD)
using the Oral Glucose Tolerance Test
What is cystic fibrosis related diabetes
CFRD occurs when people with cystic
fibrosis (CF) have a unique type of diabetes.
CFRD is not the same as diabetes found in
people who do not have CF. CFRD is a mix
of resisting insulin and not having enough of
it in the body. Therefore, the finding and
treating of CFRD is not quite like that of
other types of diabetes.
What are the common symptoms of
ξ Weight loss or trouble
ξ Unexplained decrease in lung
ξ Excess fatigue
ξ Frequent urination
ξ Frequent drinking
How common is CFRD?
CFRD is common in people with CF, even
more so as they get older. It occurs in about
20% of adolescents and 40-50% of adults.
How is CFRD diagnosed?
First, a blood glucose level will be drawn.
This is a blood test that is done without
paying attention to the time of day or to
when a meal was last eaten. If this level is
less than 126 mg/dl, it is not likely that a
person has diabetes. The CF clinical care
guidelines suggest this level should be
Second, an oral glucose tolerance test
(OGTT) will be performed every year
starting at the age of 10 years. The test
should be performed during a stable period
of health, at least 6 weeks from a recent
respiratory infection. The OGTT may also
be performed on people younger than 10
years if the health care provider suspects
CFRD. A person must have nothing to eat
or drink for at least 8 hours before this test is
done. Water is permitted.
To do an OGTT, blood is drawn to measure
the “baseline” glucose level. Then the
person will be asked to drink a 10 ounce
flavored drink (Glucola) over 5-10 minutes.
The blood sugar will be measured again two
hours later. Any person who has a blood
sugar level greater than 200mg/dL at two
hours or a blood sugar drawn at baseline
greater than 126 mg/dL, has a positive test
and will require a repeat test at least six
weeks apart from the first. If both of these
tests are positive, a diagnosis of CFRD is
made. Insulin treatment should be
When and where should screening be
done for CFRD?
Screening for CFRD should occur every
year starting at the age of 10 years. This test
may be performed as part of your routine
clinic visit at your CF Center, or if you
prefer, the test may be performed closer to
If you have any questions or concerns, call
the CF Center at 608-263-6420
The toll free number is 1-800-323-8942.
Ask for the CF Center.