Wikipedia
Oxyhyperglycemia is a special type of Impaired glucose tolerance characterized by a rapid and transient hyperglycemia (ie rise in blood glucose) spike after an oral intake of glucose, the peak of this spike being high enough to cause transient, symptom free glycosuria (i.e. detectable glucose in urine), but this hyperglycemia reverses rapidly and may even go to hypoglycemia in the later phase. This sharp downstroke overshooting towards hypoglycemia distinguishes this pathologic phenomenon from the artificial hyperglycemia inducible by an intravenous bolus dose of a large amount of glucose solution. Early dumping syndrome patients usually have oxyhyperglycemia associated with any meal or OGTT.
The Greek root oxy means "sharp" or "pointy". The OGTT curve in this condition appears sharp and somewhat pointy (at least relative to the other forms of hyperglycemia)- hence this name.
Dorlands dictionary defines oxyhyperglycemia as:
"A condition in which there is slight glycosuria and an Oral Glucose Tolerance curve that rises about 180-200 mg/dL but returns to fasting value 2.5 hrs after ingestion of the glucose."A blood level of approximately 180 mg/dL is the renal glucose threshold below which all glucose is reabsorbed from glomerular filtrate. But at blood concentrations above the renal threshold sugar starts appearing in the urine.
Oxyhyperglycemia, like other forms of Impaired glucose tolerance has also been suggested to be a prediabetic condition