San Francisco -- The annual meeting of the American Diabetes Association kicked off with a bang here yesterday. While the country's big press emphasized new results from two studies of using drugs to reduce our blood glucose levels, the hot topic here is exercise.

I'm at the ADA's 68th Annual Scientific Sessions, a huge convention of about 14,000 diabetes professionals from around the world. From glancing at the name badges of others here, I wouldn't be surprised if most are from other countries. Hosting this meeting -- which most people here just call "the ADA" -- is theMoscone Convention Center in downtown San Francisco. This foggy city on the bay is cooperating so far with beautifully sunny weather in the high 60s and low 70s -- except for a very cold outdoor reception yesterday evening.

The news in all of the papers available at my hotel trumpeted how both the ADVANCE and the ACCORD studies show that using drugs to cut our A1C levels to about 6.5 doesn't cut our risk of heart attacks, at least in the short term. The ADVANCE study did, however, show that using drugs to reduce A1C levels does improve how our kidneys function. The studies will come out in the June 12 edition of The New England Journal of Medicine and are available now online.

But only The Wall Street Journal got the point. Rather that emphasizing drugs to help us control our blood glucose levels, it referred to the journal's accompanying editorial that says that our doctors should stress other measures like smoking cessation, better diet, and more exercise. You can find that editorial, "Intensive Glycemic Control in the ACCORD and ADVANCE Trials," online.

Judging from the crowd that wanted to attend the presentation on "Current Issues in Exercise" that kicked off the convention yesterday afternoon, exercise is this year's hot button. The conference room seats about 300 people, but almost as many -- myself included -- had to listen in the hall outside. My plane arrived late so I missed the start of the first speaker's presentation.

Professor William Haskell of Stanford's School of Medicine gave the most interesting presentation, "How Much Exercise Is Enough? How Much Is Too Much?" The short answer to the first question is that health benefits are great when we get at least 150 minutes per week of moderate to vigorous exercise. While more is better, "the relationship appears to be curvilinear," according to one of his slides. That means the absolute increase in benefits becomes less and less for any given increase in the amount of physical activity.

But I gathered that we don't have any good answer to the question about how much exercise is too much. Personally, I will continue to hike, walk, and ride my bike at least 20 hours a week, not because I think I should, but rather because I feel so much better this way.

Professor Haskell make his point about the value of exercise most succinctly in this slide:

The conference organizers apologized to those of us who could not hear Professor Haskell and the two other speakers on exercise and not see them or have a seat. To make up for it, after June 17 the ADA will present it as awebcast on its site.