Most patients (or animals) with prediabetic type impaired glucose tolerance (serum glucose 140–200 mg/dL at 2 hours after OGTT) are generally not oxyhyperglycemic because:

1. Glycosuria is not necessary for mild impaired glucose tolerance (e.g. at approx 140–180 mg/dL range of blood glucose), is necessary for oxyhyperglycemia (i.e. peak >renal threshold).

2. In contrast to the commonly seen shallow OGTT curve, amplitude of the pointy spike in oxyhyperglycemia need not necessarily be restricted to only prediabetic range and in severe oxyhyperglycemia it may cross 250 mg/dL. In oxyhyperglycemia, by two hours, the glucose not only comes back to pre-diabetic range it may even start shooting below the fasting baseline.

3. In oxyhyperglycemia, both the upstroke (by 30 minutes) and down stroke (by 2.5 hr) happens quite fast which is unusual for other forms of prediabetes. In most cases of impaired tolerance, glucose levels usually do not come down as quickly, rather lasts for 2 hours or more. Whereas if the oxyhyperglycemia is due to an early dumping syndrome it may be followed by a late dumping syndrome which may even have a hypoglycemic state. For animal studies, occasionally oxyhyperglycemia is written as synonymous for impaired glucose tolerance but mostly in the right context of gastrectomy, thus actually implying its narrower meaning than impaired glucose tolerance.

In early dumping syndrome, pancreatic glucagon is augmented in the early postprandial period, probably through stimulation the catecholamines involved in the generalized autonomic surge induced by the osmotic load, but at 120 min, when most of the hypoglycemias are encountered, pancreatic glucagon is no longer detectable, likely through inhibition by GLP-1. Incretins including GLP1 and GIP also bring in the late dumping effects including the insulin rise and the reactive hypoglycemia.