(3) Glycosuria, the presence of glucose in urine, usually only occurs when blood glucose concentration is high and is therefore suggestive of diabetes. The renal threshold is the blood glucose concentration above which glucose is detectable in urine. Normally this is around 10-12mmol/L. For some people however, the renal threshold is significantly lower and glucose may appear in urine at normal blood glucose concentration. Bishop among this group. The term 'renal glycosuria' is to th entirely benign defect of kidney function. Although the finding of glucose in urine should never be ignored, it does not necessarily indicate diabetes.