Endocrinology: Diabetes & Blood Pressure

To most doctors, and consequently to their patients, the disorders that are lumped under the name “high blood pressure” seem a world apart from the disease known as diabetes. The startling truth, reported by the University of Michigan’s Dr. Jerome W. Conn to the New England Diabetes Association, is that there may be an immense and confusing area of overlap. As a result, Dr. Conn suggested, there may be more than 1,000,000 Americans who have been diagnosed as diabetics but are actually suffering from an adrenal-gland disorder requiring surgery.

Dr. Conn, 58, is one of the nation’s top authorities on a form of high blood pressure that used to be dumped into the catchall category of “cause unknown.” Not until the early 1960s was this form found to be caused by an excess of the potent hormone aldosterone (TIME, March 15, 1963), produced by the adrenal glands, which bestride the kidneys. If either gland develops a tumor, it is likely to churn out aldosterone too generously. The victim of this “primary aldosteronism” has too little potassium in his system and usually too much sodium, an imbalance that leaves him prey to intermittent paralysis, uremia—and high blood pressure.

How Would We Know? It was while he was treating some aldosteronism patients at U.M. Hospital in Ann Arbor that Dr. Conn noted the similarity to diabetes; 40% showed the same sugar-metabolism problems that plague adult diabetics. This was enough, he says, “to stimulate my imagination.” He went on to make a close study of 27 aldosteronism patients, and found that 14, when tested, showed the reduced ability to metabolize sugars. But surgery proved that all 27 had adrenal tumors.

His discovery, Dr. Conn told his Boston audience, raises a number of difficult questions. Setting aside the diabetics who develop their disease unmistakably in childhood or adolescence, what proportion of “mature” diabetics are actually suffering from aldosteronism instead? If an impaired ability to metabolize sugars develops in aldosteronism before a rise in blood pressure, “how would we know what we are dealing with?” In fact, Dr. Conn asked his colleagues, “is there such a thing as mature-onset diabetes at all?”

Double Loss. Facilities to test for primary aldosteronism exist in only a few medical centers. But if Dr. Conn is even half right, a puzzling feature of much diabetes (TIME, June 25) may be explained—why so many patients have a normal or even a high insulin level but fail to metabolize sugars properly. And some diabetes patients will certainly be referred to blood-pressure specialists, who in turn will consult endocrinologists. If the diagnosis of an adrenal tumor is confirmed, a surgeon will then have the difficult job of finding and removing a nodule only about one-sixth of an inch across. After that, suggests Dr. Conn, the patient will lose both his high blood pressure and his misdiagnosed “diabetes.”