The World Health Organisation has pointed out that due to the absence of a more specific biological marker to define diabetes, plasma glucose estimation remains the basis of diagnostic criteria. WHO recommends that venous plasma glucose should be the standard method for measuring and reporting glucose concentration in blood. However, it has also recognised that there is a widespread use of capillary sampling. Although fasting values for venous and capillary plasma glucose are the same, in the nonfasting state capillary samples will give higher results than venous samples, and glucose values require conversion which can be problematic.