Welcome to Mayo Clinic's podcast. This month's topic is prediabetes. I'm your host, Rich Dietman.

Almost 21 million people in the United States have diabetes, and the condition is on the rise, along with what some have called an epidemic of overweight and obesity. While doctors are concerned about the increasing incidence of diabetes, there's a related condition that's also worrying them. It's called prediabetes, and it's estimated to affect at least 41 million Americans, about twice the number who have diabetes. Doctors have known about prediabetes for some time, but now they understand more about the long-term damage it can do, and what can be done to prevent or slow prediabetes from developing into full-blown diabetes.

Here to talk about prediabetes is Mayo Clinic endocrinologist and diabetes specialist, Dr. Maria Collazo-Clavell. Dr. Collazo-Clavell works in the division of endocrinology at Mayo Clinic, and she's also an assistant professor of medicine at the Mayo Clinic College of Medicine. Dr. Collazo-Clavell is editor of the book titled "Mayo Clinic on Managing Diabetes" and she's a medical editor at MayoClinic.com. Dr. Collazo-Clavell, welcome.

Dr. Collazo-Clavell: Thank you.

Rich Dietman: Before we start talking about prediabetes, give us a brief overview of what diabetes is. There are two different types, right?

Dr. Collazo-Clavell: That's correct. Diabetes essentially is an abnormality in the way the body handles sugar, or blood glucose. There are two types. Type 1 diabetes, which the problem lies in the fact that the body is unable to produce insulin, which is what controls the blood glucose. That occurs because the body's immune system actually attacks and kills the insulin-producing cells. The second type of diabetes, which is by far more common, is type 2 diabetes mellitus. And there, the body's able to make plenty of insulin, there's nothing wrong with the insulin-producing cells, but the insulin itself is not as effective at controlling the glucose. What happens, over time, is the body makes more and more insulin trying to control the glucose, but it's unable to make enough, leading to a rise in the blood sugar. But, essentially, a rise in the blood glucose is what diabetes mellitus is.

Rich Dietman: So that's diabetes type 1 and type 2. What is this condition called prediabetes? Some have called it a silent condition?

Dr. Collazo-Clavell: Well, prediabetes has had many different names over the years — and even nowadays there are a couple other terms that can be used, like impaired fasting hyperglycemia — and essentially what it identifies are individuals who have glucose levels that are not within the normal range, but they're also not above the threshold to diagnose diabetes, so they're in this gray zone. And in the past, we used to feel reassured that the person was not diabetic. But the fact is that people in that gray zone are at very high risk of developing diabetes, and obviously with diabetes come a lot of other health issues. So we have tried to focus on identifying individuals that are at risk of developing diabetes, the prediabetes, and see if we can try to prevent that progression.

Rich Dietman: So it's a red flag.

Dr. Collazo-Clavell: Definitely a red flag, and again in the past we used to say, "Oh, your blood sugar is just mildly above normal," but really today we should be saying, "Your blood sugar is above normal, you're at risk of developing type 2 diabetes, here's what we should do about it."

Rich Dietman: So ... you're my doctor and you say, "Rich, you have prediabetes." What does that mean to me, both in terms of my immediate health, and also what should I be thinking pretty seriously about doing to try to prevent it from developing into full-blown diabetes?

Dr. Collazo-Clavell: Well, the mild elevations in the blood sugar that we see wouldn't cause any acute symptoms. That's what we always hear, that people may have diabetes and not know it, because an elevated blood sugar causes problems over time, but in my mind, it's still quite concerning. Because over the next few years, unless we make some changes or help you make changes, the likelihood of your becoming diabetic will be high. So the things we'll be talking about would be things that we could potentially change to alter that process. Now, we all have a genetic predisposition to certain conditions and we can't change our genes, but there are many other things that we can change, mainly lifestyle changes. We know that regular physical activity makes insulin more efficient at controlling the glucose, so being physically active even without weight loss has many health benefits. So that would be the first thing that we would talk about, how active are you, what are the obstacles that keep you from being physically active? Second is your eating habits, essentially your body is telling us it cannot handle the glucose with everything that you're giving it when it comes to diet, so we have to start making modifications, still provide your body with the nutrients it needs, but avoid the excesses, 'cause your body cannot handle that. And usually when people make changes in their eating habits and in their activity, many times there's some associated weight loss, or at least weight maintenance. Weight loss, even modest weight loss of 5 to 10 percent — in a 200-pound person, that's a 10- to 20-pound weight loss — has been consistently shown to protect against progression to type 2 diabetes. So we'll be talking about trying to introduce those changes in your day-to-day routine.

Rich Dietman: So, going back to the physical activity for just a moment, what I heard you say is that it's not absolutely critical that I lose weight, that if I just get active and do it on a regular basis, even if I'm not losing a lot of weight, but that in and of itself might help manage my prediabetes.

Dr. Collazo-Clavell: That's exactly right. There are many studies that have shown that physical activity alone — and just to give you a reference, generally about 30 minutes four to five times a week of some type of aerobic activity — has been shown to protect against developing diabetes. And probably the most recent study looking at diabetes prevention, taking individuals who have an elevated blood sugar, they're overweight, they're at risk of developing diabetes, and trying to help them institute these lifestyle changes. And of interest, only about half of the people were able to lose weight, a 5 to 10 percent weight loss, but about 85 to 90 percent of the people were able to carry out the activity that they were advised, so 30 minutes five times a week. And even though the weight loss might have been disappointing, the lowering the risk of diabetes was about 70 percent. So they were able to lower the risk of developing diabetes in over half the people, even though less than half the people were able to lose weight. So, physical activity is very important.

Rich Dietman: So the weight loss is good.

Dr. Collazo-Clavell: The weight loss is good.

Rich Dietman: But the physical activity is even better.

Dr. Collazo-Clavell: I think concentrated in the process, concentrating on trying to be more active, trying to be more conscientious about your eating habits, and not put so much focus on the scale becomes important. So even weight maintenance, if somebody is more physically active and they've maintained their weight, there's a health benefit there and sometimes people might dismiss the benefits of the activity just because they haven't lost a few pounds.

Rich Dietman: Well let's talk about food for a little bit because, as you said, that's another big part of this. In general, what kinds of foods ought I to be thinking about eating more of with my prediabetes?

Dr. Collazo-Clavell: Well, with prediabetes, essentially at that point we wouldn't be restricting people as much as having them be more conscientious about their eating habits. So, for example again, we need to avoid the excesses. Excess calories, so foods that are very high in calories or fat, it's not that you can't ever have them, because again it's a precondition, but we would say, you know, "How frequently are you having it? Maybe can you cut back the portions, the frequency," and that in itself may allow you to achieve your goals. With sweets, the same thing. Many people think diabetes, "Oh, sweets alone," but the fact is that everything we eat will turn into glucose. But again the excesses, maybe three cookies at a time might not be the best thing, but you can still enjoy one, so it's trying to make changes that you can adhere to, but they're still changes that are good for your health.

Rich Dietman: And talking about weight management for a minute, is it really the fact that so many of us have prediabetes, or diabetes, largely due, in this country, in the United States, due to the tremendous amount of overweight and obesity? Is it really that?

Dr. Collazo-Clavell: Well, the rise in the prevalence of diabetes really has been observed over the past 20 years. So our genetic makeup has not changed that dramatically in the past 20 years. And it follows very closely the rise in what we call the prevalence, meaning how frequent obesity is. And probably the most concerning is that it's not only affecting adults, but it's affecting adolescents, it's affecting children — so that we're all heavier. So the risk of developing diabetes at a much younger age puts our health at much higher risk because it's more years of having diabetes, more years of your body being submitted to the damages of potentially elevated blood sugars, so it escalates when it comes to the threat to our health.

Rich Dietman: So I've been diagnosed with prediabetes and, for whatever reasons, just haven't been able to get my blood sugar down to where you think it should be through exercise and diet. What's next? Is there something else that can be done?

Dr. Collazo-Clavell: Well, usually we do try to focus on what are the obstacles and what's reasonable to try to achieve when it comes to changes in lifestyle. And usually most people know what they have to do, there's just obstacles in the way, whether it's time or motivation, whatever. Now there's a lot of debate on should we be using medications to try to prevent this progression to type 2 diabetes, and there are many studies that have actually looked at that. They've mainly used medications that again improve insulin action, they're called insulin sensitizers. And when you start somebody who has a mildly elevated blood sugar on one of these medications, the vast majority of them will have a normalization of their blood sugar. The debate is, here we're submitting, however, individuals to medications, with potential risks to them as well, and it still remains to be seen, is that something we should be doing routinely, does the benefit of starting a medication earlier on, is it really worth long-term risk of starting an individual on medication? We do it because we're concerned, obviously, that the blood sugar might be rising, despite efforts, we want to get that glucose under control. But I always try to encourage my patients to do as much as they can with their lifestyle changes because that means that we might be able to defer the initiation of medication, having to assume the risk of medication, and the fact is that the better an individual does with their eating and activity habits, the more effective the medicines are.

Rich Dietman: Is a person with prediabetes at the same kind of risk for some of the serious illnesses that come, or that can come, with diabetes? Things like cardiovascular disease, things like that?

Dr. Collazo-Clavell: Well, prediabetes is a component of what we hear now of the metabolic syndrome, and again the metabolic syndrome takes individuals that have a mild abnormality in their blood sugar — they may or may not be diabetic — mild abnormalities in their blood pressure — they may or may not be on a hypertensive medication. And again this is all kind of a continuum, meaning that, with any abnormality in the glucose, the blood pressure, the blood fats like cholesterol and triglycerides, there is increased risk as opposed to having them be normal. So yes, that's the concern, that this process that threatens the health of our patients, including increasing the risk of heart disease, has already started, and we want to make changes to try to prevent those potential problems.

Rich Dietman: And going back to physical activity and diet and nutrition, it sounds like you're saying that if I really pay attention to these things that I could, the potential is there that I could move out of this prediabetes back into the normal range, that I'm not stuck here.

Dr. Collazo-Clavell: That's right, but even in individuals who, for example, if their blood sugar might remain mildly above normal, but it doesn't progress, meaning every year they're putting in their efforts at staying active, they might not even be losing weight, they might be maintaining their weight, meaning their efforts at diet and exercise are enough to maintain their weight, but if I'm seeing that person with just a mildly elevated blood sugar for the next 10 years and they haven't progressed on to type 2 diabetes, that in itself is a success. Because if that person would not be participating in those things, in those activities, the chances are that within five years they would have become diabetic. So again, a lot depends on how we judge our intervention, and as long as we're protecting people against progressing on to diabetes, I do see that as a success, even if the blood sugar is still mildly elevated.

Rich Dietman: So what are the take-home messages as far as being on the lookout for and managing prediabetes?

Dr. Collazo-Clavell: Well, I think all of us should try and stay physically active, and I know that becomes quite challenging in our current society. But any activity is worth doing, so walking throughout your day, going up a flight of steps, if you have the time to put 20 or 30 minutes into a formal exercise program, that's great. Try to be reasonable with your eating habits, this doesn't mean that you have to completely do without your favorite foods that might be labeled with fat, although we don't like to think that way, but try to be reasonable to monitor the portions. And those are the key. But if you know you might be at risk for diabetes — and that means that you have a family history of diabetes, if you're overweight, if you're inactive — certainly get screened or have your blood glucose checked, but you don't have to wait to have a glucose be abnormal to start making healthy changes. So if you're able to recognize, I'm not as active as I could be, and there are a few minutes of my day where I could be more active, I would say go ahead and do it.

Rich Dietman: Thanks very much, Dr. Collazo-Clavell. We've been talking with Dr. Maria Collazo-Clavell, endocrinologist, and an expert in the treatment of diabetes and prediabetes at Mayo Clinic. Dr. Collazo-Clavell is also editor of the book "Mayo Clinic on Managing Diabetes" and she's a medical editor with MayoClinic.com. I'm Rich Dietman.