ORAL GLUCOSE TOLERANCE TEST. A RESEARCH PROJECT MATERIAL ON BANKING AND FINANCE
In the late 1970s, both World Health Organization (WHO) and the National Diabetes Data Group produced new diagnostic criteria and a new classification system for diabetes mellitus (World Health Organization, 1985). This brought order to a chaotic situation in which nomenclature varied and diagnostic criteria showed enormous variations using different oral glucose loads. In 1985 WHO slightly modified their criteria to coincide more closely with the NDDG values. There are now many data available, and also much more aetiological information has appeared. It seemed timely to re-examine the issues and to update and refine both the classification and the criteria, and to include a definition of the “Metabolic Syndrome” (World Health Organization, 1985).
An American Diabetes Association (ADA) expert group was convened to discuss these issues. It published its recommendations in 1997. WHO convened a Consultation on the same subject in London, United Kingdom, in December 1996 (The Expert Committee on the Diagnosis and Classification of Diabetes Mellitus. Report of the Expert Committee on the Diagnosis and Classification of Diabetes Mellitus, 1997). In general, the ADA and WHO groups reached similar conclusions.
1.1 LITERATURE REVIEW
One hundred years ago, the answer seemed easy enough. Diabetes was a condition with characteristic symptoms and glucose in the urine. Furthermore, those affected were obviously unwell and would deteriorate or die in the absence of effective therapy. Physicians such as Elliot Joslin (1870-1962) were well aware that some individuals had a higher than normal blood-glucose without symptoms, and even used the term “prediabetes” to describe them, but did not consider the diagnosis useful to make .
The 1930s showed increasing awareness of the problem of late complications of diabetes. Physicians became aware that insulin was not a panacea and that the life expectancy of insulin was reduced by conditions such as diabetic nephropathy and heart disease (Finch , Zimmet , Albert, 1997). Fifty years were to pass before it was demonstrated that treatment directed towards careful control of blood-glucose levels could prevent or delay the small vessel complications of diabetes.