Diagnosing diabetes and gestational diabetes

Patient: Why is it when they check for diabetes in a pregnant woman they do the gluecose check but when they check someone not pregnant they use a blood test alone?

Doctor: Diabetes can be diagnosed if a fasting plasma glucose level, after 8 hours, is > 7.1mmol/L or a random plasma glucose level is >11.1mmol/L. It can also be diagnosed after a oral glucose tolerance test  where the person being tested fasts for at least eight hours, is then given a 75 g glucose load (in the form of a very sweet drink), and the blood sugars are measured at one or two hour intervals. Diabetes is diagnosed if after two hours the plasma glucose level is > 11.1mmol/L. Patients with plasma glucose >7.8 mmol/L but <11.1 mmol/L, two hours after a 75 g oral glucose tolerance test are considered to have impaired glucose tolerance. In pregnancy, there is an increased glomerular filtration rate in the kidneys, and as a result in many pregnant women there is leakage of glucose into the urine. This does not diagnose diabetes, but would prompt the use of either a fasting plasma glucose test or an OGTT to confirm a diagnosis of gestational diabetes.


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