Can undiagnosed diabetes cause high and low blood sugars? From what I have heard, diabetes is only diagnosed when a person has abnormally high blood sugars. Is this true?

Diabetes mellitus is a major, if not THE major, cause of elevated blood glucose concentrations. But, just as “not all that glitters is gold,” not all elevated glucose is diabetes. But, it usually is. Please see our web page on the Classification and Diagnosis of Diabetes to read about current diagnostic criteria or definitions as to what degree of elevated glucose is consistent with a diagnosis of diabetes mellitus.

I have often heard, from colleagues, that they have seen diabetes preceded by LOW glucose levels. But, medical textbooks do not detail this phenomenon and I am not certain that there is a cause and effect here. If you sneeze and get run over by a bus, it does not follow that sneezing causes motor vehicle accidents. But, it could in the wrong place at the wrong time. NORMAL persons can, on occasion, get a low blood glucose. And, patients with diabetes formerly had normal glucose readings. I don’t think that the issues relate.

DS