Ten randomly selected Nigerian diabetic patients who were given an intramuscular insulin-reaction test (I.M.I.R.T.) to determine their renal threshold for glucose were found to have a very low mean renal threshold. This finding could be of great significance in the clinical management of Nigerian diabetics in whom relatively high urine-sugar levels may be found despite low blood-glucose levels. It is suggested that the I.M.I.R.T. be routinely carried out, where possible, for more accurate management of the Nigerian diabetic patient.