Defining and Understanding Gestational Diabetes
Read Missy's last post, How Do I Know if I Have Gestational Diabetes?
Gestational diabetes was only added to the World Health Organization's list of diagnostic codes in 1979. Was this a new phenomenon in 1979? Physicians had known about diabetes for centuries. Had doctors just discovered gestational diabetes in 1979? Insulin had been used to treat diabetes since 1921 and oral medications since the early 1960s. So, why was gestational diabetes not given an official medical code until such a late date? The answer to that question has a lot to do with our social understanding of health and illness.
Advances in medical technology, along with a new interest in the early detection of disease, have fundamentally changed the way we view illness. This has been especially so for chronic illnesses like diabetes. But, diabetes was not always considered a chronic illness. Until the discovery of insulin in 1921 and the realization about a decade later that another form of diabetes, now called Type 2, could be present without any symptoms for years, diabetes was thought to be a fatal disease. Young patients died within months of diagnosis. But, when insulin commuted the death sentence for these young patients, they were not cured of the disease. Rather, they now had a chronic illness, much like their counterparts with Type 2 diabetes. This set of changes happened at the same time that the modern health care market began to take shape, with its third-party payer systems like insurance companies and with its profit-oriented businesses like pharmaceutical companies. Patients, including diabetes patients, became consumers and found themselves classified in part by their socio-economic status.
The new connection between health status and social status arose during a time of intense medical discoveries and advances. For the set of symptoms that would eventually be called gestational diabetes, several technological advances had an impact. These included a change from urine testing to blood testing with diabetes, a move from the home to hospitals for birthing, and a new practice of using statistics to determine who was at risk for certain diseases. These developments were shaped by society's increasing interest in preventing chronic illnesses like heart disease and diabetes. With the advent of vaccinations and antibiotics, chronic illnesses began replacing infectious illnesses like smallpox and tuberculosis in prevalence and in importance.
When lab tests for measuring blood sugar became more accurate and easier to perform, they replaced the old method of checking urine for the presence of sugar. If blood sugar rises too high, the extra sugar will pass into the urine and for decades physicians used urine testing to diagnose diabetes and to determine how well treatment was working. The amount of blood sugar that any one individual can tolerate before it "spills" into the urine varies considerably. So, even though testing blood is more accurate, some believe that it takes away individual differences in how much blood sugar is too much. By setting a specific number for a blood test, some people who would not have been diagnosed with diabetes through urine testing (because no sugar "spilled over" into their urine) would now be labeled with diabetes or pre-diabetes. Or, perhaps, these people were now being identified whereas before they were going undiagnosed. There is much debate over which perspective is correct.
Another technological change in the early twentieth century was that women began to deliver their babies in hospitals instead of at home. Rates for problems with deliveries decreased dramatically, but pregnancy and childbirth began to be treated increasingly like the illnesses that brought sick people to hospitals. The new medical specialty of obstetrics brought a different approach to pregnancy, one that focused on potential problems and how to identify and eliminate them. For pregnancies that may now be associated with gestational diabetes, this change in medical focus brought increased attention. So, although pregnant women often had sugar appear in their urine toward the end of the second trimester without any obvious problems, this phenomenon came under increased scrutiny by doctors and researchers.
At the same time that urinary sugar became suspect as abnormal during pregnancy, women who had already been diagnosed with diabetes were becoming pregnant for the first time. The advent of insulin therapy had made this possible. Women who had full-blown diabetes often had terrible endings to their pregnancies, though, frequently losing the child and sometimes even dying themselves. Even though gestational diabetes is completely different from a woman who already has diabetes becoming pregnant, the fear of potentially life-threatening complications made the public view these two unrelated experiences as similar if not exactly the same.
Finally, during this period of the mid-twentieth century, we saw the beginning of the use of statistics to create a broad picture of health and illness in society. Life insurance companies assessed their clients' life expectancies. Public health officials tried to determine what factors played a role in chronic disease. And, the media told the public who was sick and what doctors were doing about it.