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Caption: Dr Samuel Dagogo-Jack, lead researcher, explaining the prediabetes study to a prospective volunteer at the Methodist South Health Fair this year.

Last November, Memphis Medical News reported on a local UT study sponsored by the National Institutes of Health (NIH) to determine the biological triggers that push people from normal glucose to pre-diabetes. Pre-diabetes is a health condition known as impaired glucose tolerance, representing a score on the blood glucose test that is in between normal and diabetes. The study is also aimed at understanding the mechanisms for the ethnic and racial differences in the development of diabetes, which affects African-Americans at twice the rate of Caucasians. This study will compare blacks and whites who have one or both parents with type 2 diabetes.

The premise of the study comes off the heels of a Diabetes Prevention Program study which reported that Caucasians, African-Americans and all other minority groups, once they reached the pre-diabetic stage, progressed to diabetes at exactly similar rates. This led Samuel Dagogo-Jack, MD, program director of the UTHSC division of endocrinology, diabetes and metabolism, to postulate that the driving force for the eventual higher rates of diabetes in African-Americans must be initiated prior to the pre-diabetes stage.

Two years into the 5-year study, unexpected results have been yielded related to diabetes and hypertension. Dagogo-Jack, lead investigator on the study, explained that after the first 200 enrolled, the team decided to look at how blood pressure related to blood glucose in the participants.

It is generally believed that the patterns seen in hypertension and diabetes would be reflected or reproduced in prehypertension and pre-diabetes. In this study, investigators analyzed the coexistence of pre-diabetes and prehypertension and further assessed changes in blood pressure in relation to blood glucose in African-American and Caucasian offspring of type 2 diabetes parents. Unlike the well-known ethnic disparity in high blood pressure, the study showed similar blood pressures in blacks and whites who had a genetic risk for diabetes. However, 56 percent of these offspring of diabetic parents had either high blood pressure or prehypertension, according to the abstract presented at The Endocrine Society's annual meeting this year.

"We found that 37.2 percent of the offspring of diabetic parents had prehypertension. This is a staggering number compared to the 15 percent prevalence of non-hypertensive "elevated BP" reported for persons of similar age in the general population," explained Dagogo-Jack. "Unlike the well-known ethnic disparity in hypertension, our data showed similar blood pressures in African-American and Caucasian offspring of type 2 diabetes parents. Thus, a genetic risk for diabetes seems to abrogate ethnic differences in hypertension/prehypertension rates."

This is serendipitous, Dagogo-Jack said, because researchers were previously unaware how high the frequency of prehypertension would be in people with pre-diabetes.

The American Diabetes Association reports that 54 million people in the U.S. over age 20 are pre-diabetic. Current medical practice does not require people to be screened for the condition, which has no symptoms; however knowing someone has pre-diabetes immediately identifies them as being at high risk for future diabetes. The rate of progression from pre-diabetes to diabetes is approximately 10 percent a year. In five years half of the pre-diabetic population has converted and in a decade almost every pre-diabetic has moved on to full blown diabetes. Prehypertension works in much the same way, a near-high blood pressure that raises the risk of full blown hypertension.

Approximately 25 million Americans have diabetes and 70 million have hypertension. It has been estimated that at least twice as many people have pre-diabetes and pre-hypertension as compared to those who have diabetes and hypertension, said Dagogo-Jack.

"Efforts to prevent diabetes could well preempt and prevent high blood pressure as well as their precursors—pre-diabetes and prehypertension," suggested Dagogo-Jack.

Most importantly, he said, subjects who had pre-diabetes were more likely than those with normal blood sugar to have either high blood pressure (23versus 16 percent, respectively) or prehypertension (42 versus 33 percent). The prehypertension prevalence in pre-diabetic subjects was similar among blacks and whites (40 versus 46 percent).

"The single most important application of these findings would be a policy change that mandates 'one-stop shopping' for the prevention and management of hypertension-diabetes," maintained Dagogo-Jack. "The two conditions as well as their precursors –prehypertension and pre-diabetes – are literally 'joined at the hip.'"

When the study is completed, he added, it will benefit society by being the first study to discover the earliest determinants and predictors of escape from normal glucose metabolism in real-time.

"Because we're tracking progression from normal to pre-diabetes, rather than full-blown diabetes, our discoveries will help direct preventive efforts at a timely stage before people become "locked" in to diabetes," Dagogo-Jack concluded, adding his dream is "that this study will shift clinical thinking and diagnostic practices away from established disorders and more toward early recognition and intervention at the pre-disease stage."

The pre-diabetes study is still accepting volunteers, with 200 more needed. Dagogo-Jack hopes to close recruitment in 2009.

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