Advantages/disadvantages and roles
Urine testing is easy to perform by simply passing urine onto a test strip, or using reagent compounds, does not require a meter with associated maintenance and battery replacement needs, does not require lancets with the associated safety and disposal issues, is not complicated by issues relating to the withdrawal of old and introduction of new meter models and strips and confusion and wastage caused by the often large number of models available. It is therefore a more appropriate technology for many settings.

Before the advent of blood glucose monitoring in the 1970s, urine glucose monitoring was universally used, with many people able to maintain good control. Blood glucose monitoring has now replaced urine monitoring in most resource–rich settings. However, insistence on blood glucose monitoring in economically disadvantaged settings could result in no monitoring at all, which would be a major loss compared to the very important information available from urine glucose monitoring. The withdrawal of visually readable blood glucose strips has made blood monitoring even more inaccessible to people with low incomes. The continuing availability of urine glucose testing is a critical issue in such circumstances, even beyond the time when cheaper blood glucose strips may become available.

Studies in some economically developed countries indicate that significant percentages of the population cannot afford to purchase diabetes supplies on an ongoing basis. Urine glucose monitoring is a viable option in such circumstances, with occasional blood glucose measurements to help ensure acceptable control.

Interpretation
The limitations and proper interpretation of urine glucose test results need to be understood. These include that urine testing gives the results since the last time urine was voided. If the urine is free of glucose, it is an indication that the blood glucose level is below the renal threshold, which can vary, but is usually accepted as corresponding to a blood glucose level of 10 mmol/l (180 mg/dl). Results also do not distinguish between moderately raised and grossly elevated blood glucose levels. A particular concern is that a negative test does not distinguish between normoglycaemia and hypoglycaemia. In pregnancy, urine testing is less reliable because the renal threshold for glucose can drop significantly.

Some strips also allow for the measurement of urine ketone and protein levels. Urine ketone measurement is particularly useful in the early recognition and management of diabetic ketoacidosis.

Summary
Urine glucose monitoring is a viable, cost–effective way of monitoring diabetes control, especially when the cost of blood glucose monitoring makes it inaccessible or when people do not wish to perform blood testing.

Urine glucose monitoring has a number of limitations and is not a substitute for blood glucose monitoring, for example it cannot distinguish between low and normal blood glucose levels, or high and very high blood glucose levels, and is less reliable in pregnancy. However, it is particularly helpful in persons at low risk of hypoglycaemia and whose blood glucose levels are not too high and generally stable. Occasional blood glucose measurements should be made to help monitor acceptable control.

Increasingly, emphasis is being given to blood glucose monitoring, for example through advertising, without commensurate publicity being given to the valuable role of urine glucose monitoring. This lack of information may result in health care professionals, people with diabetes and governments downgrading or becoming increasingly unaware of the importance and usefulness of urine glucose monitoring in appropriate circumstances, in both developing country and some developed country settings.

References:
Morris LR, McGee JA, Kitabchi AE. Correlation between plasma and urine glucose in diabetes. Ann Intern Med, 1981, 94 (4 Pt 1), 469–71
Rotchford AP, Rotchford KM, Machattie T, Gill GV. Assessing diabetic control– reliability of methods available in resource poor settings. Diabet. Med, 2002, 19(3), 195 – 200
Diabetes Atlas second edition, International Diabetes Federation, 2003, Chapter 5, 193–205 – Access to Insulin and Diabetes Supplies

Source: International Diabetes Federation