What is Pre-diabetes, and How does it Affect my Health?

Bill was a fit man for his age and appearing to be in good health. He said, “I am just retiring, so I want to make sure I am properly evaluating my health.” He came to see me to get blood-based laboratory testing. As I evaluated his medical records, I noticed a couple of times when his fasting blood sugars had been running a little high. They were not in the pre-diabetic range but were above the optimal range of 70–85; they were running just above 90.

“I think one of the best tests you could do is a two-hour glucose tolerance test,” I suggested. The test came back a few days later, showing a two-hour blood sugar well above 140, indicating advanced pre-diabetes. Bill wasn’t overweight and had been exercising three to four times a week, so these results caused him to reevaluate his health.

“Clearly,” he said, “what I have been doing is not enough to overcome the natural genetic tendency I have toward pre-diabetes or diabetes.” So at the next appointment, he came in with his list of many questions and said, “OK, what do I need to do that will be enough to reverse this pre-diabetes?” So he went through our twelve-week program designed to optimize blood sugars and correct the underlying causes of his health risk.

Through that process, he learned simple strategies that, when brought together, helped him totally reverse his pre-diabetes. One of the things Bill learned in the program was that the timing of exercise is really important. Remember, Bill was lean and fit—he already exercised more than most men. His blood sugars, before meals, were essentially fine—but not his blood sugars after meals. So he learned two primary strategies: to note what kinds of meals caused the biggest spike in his blood sugars—and also to note the time of his exercise that had the greatest impact on lowering his blood sugar spike after meals.

What he learned was that exercising immediately after a meal had the potential to lower his blood sugars anywhere from one to three points for every minute he exercised. So for instance, if someone’s blood sugar is typically ninety points higher than it should be one or two hours after a meal, but now they go out right after eating and exercise moderately to briskly for thirty minutes, there is a good chance they could lower their blood sugar (at three points for every minute of exercise) by up to ninety points, bringing their high blood sugar down to a much healthier level.

The second thing Bill recognized is that he needed to learn how to balance his meals. He needed to know how to use whole plant-based foods that incorporated nuts and seeds in moderate amounts, with their healthy fats and proteins. This would slow down the absorption of sugar from his meal, so his sugar would not spike nearly as much. He also needed to learn how to choose healthy starches. Not all starchy complex carbohydrates are healthy starches—these need to be unprocessed, high in fiber and full of nutrients before they help control blood sugar levels and ultimately, the health of our heart and blood vessels.

Bills story is one of many examples showing the importance of proper testing and how it guides us in making simple changes that can transform our health and greatly lower our risk for future disease. That is why I believe one of the best health assessment tests available today is the two-hour oral Glucose Tolerance Test (GTT for short). Typically, only the fasting and two-hour glucose levels are now tested in the GTT. But the most likely time to see an elevated blood sugar (glucose) is at the one-hour point after drinking 75 grams of Glucola (a standard carbonated glucose drink used to see how high blood sugar goes). So I always add the one-hour glucose test to the GTT. In addition, I always add the fasting and two-hour insulin test. Even in patients who have completely optimal blood sugar responses to the GTT, the insulin levels are among the first risk factors to indicate a risk to health.

While testing insulin levels is not currently part of standard recommendations, I learned the value of testing insulin several decades ago by paying attention to the advice of Dr. Nancy Bohannon, a preventive endocrinologist, director of the Cardiovascular Risk Reduction Program at St. Luke’s Hospital in San Francisco, and professor at UCSF. In 1991 Dr. Bohannan—who sub-specializes in diabetes prevention and management—gave a lecture sent out to family practice physicians in “Family Practice Audio Digest.” As part of the talk, she explained how the fasting insulin should always be less than 10 microIU/mL. Because of my willingness to listen to one of the world’s leading experts and not simply wait the average of twenty-five to thirty years it usually takes for good evidence to be fully accepted by the average clinician, I was able to effectively counsel thousands of patients as to their future health risk and how to transform that risk through comprehensive lifestyle medicine.

Why is this important? Because having a high insulin level predicts a three-fold increase in risk toward developing heart disease. In addition, elevated blood insulin is a major contributor to the development of high blood pressure and is closely associated with increased prostate, breast, and colon cancer risk.

Now, back to Bill’s story. Once we learned that Bill had advanced pre-diabetes, I discussed the relationship between blood sugars, insulin, and blood pressure with him. For many years he had struggled with hypertension, even while on medications for his blood pressure.