Health Update

By TYRONE M. REYES, M.D.

Last year’s top health stories are a reminder that so much of health and medicine seems to reside stubbornly in the details. For example, blood sugar control as a general proposition in diabetes isn’t a bit problematic. But sorting out just how low it should go, in which patients, and by what means — that’s difficult. Clinical trial results in 2008 steered patients and doctors away from an all-out approach that emphasizes super low levels toward a well-rounded one that takes into account cardiovascular risk factors. Similarly, we know that controlling high blood pressure is important, but clinical trial results in 2008 laid to rest some old theories by showing that this is also true for people ages 80 and older. I’m just as enthusiastic as anyone about advances in stem cell research and genomics. But it gives you a sense of the complexities and the long road ahead if basics such as blood sugar and blood pressure control are still being worked out.

Blood Sugar: How Low Should It Go?

People with type 2 diabetes are encouraged to keep their blood sugar levels low, and the usual goal is a glycated hemoglobin (HbA1c) level of seven percent or lower (the percentage of “sugary” hemoglobin is a good way to assess blood sugar levels over time, rather than depending on the snapshots of single blood sugar measurements). But is seven percent ambitious enough? Results from three clinical trials last year showed that the single-minded pursuit of low blood sugar levels is probably not the best approach to type 2 diabetes, particularly in people ages 60 and older.

The ACCORD trial got the most attention because it was stopped early after an interim analysis found that more people in the intensive treatment group (an HbA1C goal of below six percent) had died than those with more conventional blood sugar goals (between 7 and 7.9 percent).

The blood sugar goal was more relaxed (6.5 percent) in another trial, and the intensive treatment group did have fewer deaths and heart attacks than the conventional treatment group, but the difference wasn’t statistically significant. A third trial, a Danish study called Steno-2, tested a more holistic approach: the 6.5 percent goal along with targets for lower total cholesterol, triglycerides, and blood pressure. It worked to slice heart attacks and other cardiovascular “events” in half.

But it’s important to stress that people with diabetes should continue strict blood sugar control. Data show that it lowers the risk of kidney disorders, eye diseases, and other problems related to damage of small blood vessel (microvascular disease).In fact, a British report last year suggested that tight control may bring about changes at the cellular level that create a “legacy effect”: protection from vascular problems that extend years to decades, after blood sugar was tamped down.

But last year’s bumper crop of diabetes research has shown that it’s unwise to be overzealous about blood sugar lowering — moderation in all things! — and certainly not without also attending to risk factors like high blood pressure and cholesterol.

80 Ain’t Old

Doctors used to be taught that high blood pressure was a blessing in old age because the extra oomph pushed blood through narrow, atherosclerotic arteries. But the age limit for controlling high blood pressure — usually with medications — has crept up as research results have shown that it prevents strokes, heart attacks, and heart failure in the old and young alike.

Last year, results from the Hypertension in the Very Elderly Trial (HYVET) topped off that trend by showing that even in an age group once viewed as being extremely old — those 80 and older — reining in high blood pressure pays off. After two years, the treated group in the study had lower rates of heart failure, strokes, and overall mortality. The HYVET study subjects were noted to be healthier than the usual average group of 80-plusers. HYVET is one more evidence that the age for effective medical intervention — be it pills, surgery, or devices — is getting older and older.

iPS: What These Stem Cells Might Do For You

Last year, several research groups discovered ways to genetically tinker with adult cells so they look and behave like stem cells from embryos. These reprogrammed cells — called induced pluripotent stem cells (iPS) cells — have given researchers another source of stem cells besides embryos. One catch: The retroviruses and two of the genes used to create iPS cells could turn them cancerous. For that reason and others, scientists don’t want to abandon embryonic stem cell research, but iPS cells do eliminate many of the ethical issues dogging stem cell research because embryos aren’t involved. They could also make immunological rejection a moot point because with iPS cell therapy, the patient’s own cells would be used.

Important iPS findings popped up left and right last year. Skin cells from two older patients with amyotrophic lateral sclerosis (Lou Gehrig’s disease) were transformed into iPS cells and then coaxed into becoming neurons and other cells that might be used to treat the disease. Insulin-producing pancreatic cells were made from iPS cells that came from human skin. Harvard researchers created several lines of iPS cells from patients with genetically based diseases like Parkinson’s and Huntington’s. And as 2008 was ending, two research teams reported that they had created iPS cells without retroviruses or the two cancer-causing genes, another step forward toward the day when stem cell therapy will leave the lab and enter the clinic.

Seeing Right Through You And Its Dangers

A half-dozen imaging technologies allow doctors to see what’s going on inside the body. The workhorse, though, is computed tomography (CT), which uses a computer to assemble multiple cross-sectional x-rays into remarkably detailed pictures. The basic technology is nothing new — it’s been around for more than 30 years — but a new generation of machines, called multidetector CT scanners, is making the pictures even faster and incredibly sharp.

Speedy CT scanners are proving to be especially valuable in hospital emergency departments, where time is of the essence. It’s now routine at many modern hospitals for patients with chest pain to get a CT scan of their coronary arteries to see if they are diseased. Depending on the result, hospitalizations may be avoided. CT scans are also a mainstay of emergency departments; by some estimates, doctors now order more than a hundred thousand CT scans in the Philippines last year, double the number ordered a decade ago.

But are we going to pay a price for all these pictures? The radiation from CT scans is much higher than from traditional imaging tests. Starting in 2007, researchers at Columbia University in New York have published several provocative papers about the cancers that these CT scans may cause. According to their projections, the current exposure to CT scans might be responsible for between 1.5 percent and two percent of all cancers a few decades from now (it takes years for the cancers to develop).

There are, however, several technical adjustments to the CT scans that can lower the per-scan dose quite a bit. Still, scans are often repeated for no good reason; doctors need to eliminate those unnecessary do-overs. And using other imaging tests when possible could reduce radiation exposure.

Gene Tests: Progress And Pandora’s Box

Genetic tests might take some of the guesswork out of medicine. Someday, the results may be used to predict the diseases you are most at risk for, so you could adopt the most effective prevention behaviors. Other tests will be used to guide treatment. Genetic tests are already used in the prescription of some expensive cancer drugs, such as trastuzumab (Herceptin) for breast cancer. (more…)