by Robin
(Maine)
Submitted by Robin, Maine
Hi,
I have myasthenia gravis and take prednisone. My non-fasting glucose level was 112 mg/dL, measured about three hours after breakfast.
I cannot fast easily because I need to take my medicines with yogurt so I can swallow them. Is this glucose level too high?
Answer by Dr. Albana Greca, MD, MMedSc
Hello Robin,
A glucose level of 112 mg/dL three hours after breakfast is not high enough to diagnose diabetes and is generally reassuring. However, it must be interpreted as a non-fasting or random result—not as a fasting glucose test.
A fasting plasma glucose test requires at least eight hours without any caloric food or drink. Yogurt contains carbohydrate, protein and calories, so taking medicine with yogurt ends the fast even when the amount is small.
The different diagnostic tests and their preparation are explained in our guide to fasting glucose, HbA1c and other blood tests for diabetes.
A random plasma glucose can be measured regardless of meals. Diabetes may be diagnosed from a random value of 200 mg/dL or higher only with classic symptoms or a hyperglycemic crisis. A result of 112 mg/dL is far below that threshold.
One random result cannot prove that glucose is normal at every time of day. Our article on interpreting normal and borderline blood sugar readings explains why timing and repeated patterns matter.
Prednisone can make the body more resistant to insulin and can reveal or worsen high blood sugar, especially with higher doses or longer treatment.
With morning prednisone, fasting glucose may remain normal while glucose rises after lunch or later in the day. For this reason, current diabetes guidance advises that screening for glucocorticoid-related hyperglycemia may be more useful with a random reading or a reading one to two hours after a meal rather than relying only on fasting glucose.
You can read more about this effect in our answer on how systemic steroid medicines may raise blood sugar.
An HbA1c test does not require fasting and can be drawn at any time of day. It estimates average glucose over approximately the previous two to three months, although it may not fully reflect a very recent prednisone dose change or a short steroid course.
The meaning of the result is covered in our article on HbA1c and average blood glucose.
Your clinician may choose one or more of the following:
Do not skip prednisone or other myasthenia gravis medicines simply to complete a fasting test. Prednisone should not be stopped suddenly without medical guidance, particularly after ongoing use.
Tell the clinician that you need yogurt to swallow your medicines. A non-fasting test or safe medication timing can then be arranged. A pharmacist should confirm whether each medicine can be taken with yogurt.
Ask for follow-up if the prednisone dose is increased, treatment will continue for a long period, or you develop increased thirst, frequent urination, blurred vision, unusual fatigue, recurrent infections or unexplained weight loss.
Contact the clinician if repeated after-meal or random readings are elevated. Seek urgent care for very high glucose accompanied by persistent vomiting, severe dehydration, confusion, deep or rapid breathing, or marked drowsiness.
Your glucose of 112 mg/dL three hours after breakfast is reassuring and is not in the diabetes range. It should not, however, be relabeled as a fasting result.
Because prednisone can raise glucose later in the day, ask your clinician whether an HbA1c and selected one-to-two-hour after-meal readings would provide a better assessment. Continue your myasthenia gravis medicines exactly as prescribed unless the treating team changes them.
Hope this helps.
Dr. Albana Greca
Click here to post comments or follow up
Ask the Doctor now? Simply click here to return to Diabetes Test and Levels.