Our three year old daughter was diagnosed with type 1 diabetes about 2 months ago, and in an effort to educate herself about her sister’s experiences, our eight year old took her own blood sugar, and came up with a 189 mg/dl [10.5 mmol/L] reading. I have repeated the test on her myself several times, consistently come up with a 180 mg/dl [10 mmol/L] reading, and I was under the impression that anything above 140 mg/dl [7.8 mmol/L] was not probable in a person without diabetes, regardless of what they ate, or when the blood sugar was taken. Am I seeing the beginnings of diabetes in this daughter as well? Should I be concerned enough about this at this time that I should subject her to a glucose tolerance test? We have six children and I am sick at heart at the thought that even one more of them could be afflicted with this disease.

Your daughter is at an increased risk for diabetes because her sister has type 1 diabetes. Any blood sugar above 140 mg/dl [7.8 mmol/L] is clearly abnormal. I would recommend discussing this promptly with her pediatrician who can direct any further testing that may be necessary.

MSB

[Editor’s comment: Testing for diabetes should include blood sugar levels performed by a medical laboratory. The timing of the sample (fasting, random, or postprandial) would influence how high a level is considered abnormal. See Classification and Diagnosis of Diabetes for further information.

Occasionally, lab blood sugar testing might be normal in an early case of diabetes, repeat blood sugar testing at the same or a different time, or performing a glucose tolerance test, might be appropriate if there is a high suspicion of diabetes despite normal initial testing. Another test, the glycosylated hemoglobin, might be used to help confirm a suspected diagnosis of diabetes, but the GHB (also called HbA1c or A1c) is not usually considered as appropriate to make an initial diagnosis. Antibody testing is occasionally done as a screening test in high-risk situations, or as confirmatory of type 1A (autoimmune) diabetes, but is not part of routine testing.

Home glucose testing, if done, might be positive, which would make the situation more urgent to get lab testing done to confirm the abnormal results.

WWQ]