Is Diabetes a Cardiovascular Risk Equivalent?

This transcript has been edited for clarity.

Jay H. Shubrook, DO, FAAFP, FACOFP: Hi. I'm Jay Shubrook, a board-certified family physician and fellowship-trained diabetologist at Touro University California.

Mark L. Villalon, MD, FACC: My name is Mark Villalon. I am an interventional cardiologist at NorthBay Healthcare in Fairfield, California.

Shubrook: Today's topic is one that I think we've all thought about and quite often quote. Is diabetes a cardiovascular risk equivalent?

Mark, I've worked with you. I love the work that we do together. To start this conversation, we need to know what it means when we ask, "Is diabetes a cardiovascular risk equivalent?" What's your take on that?

Villalon: Jay, thank you for having me. Diabetes, as we all know, is a progressive metabolic disease characterized by insulin resistance and eventual functional failure of pancreatic beta cells. It is the impaired glucose metabolism that is linked to higher rates of atherosclerotic cardiovascular disease (or ASCVD), morbidity, and mortality.

This is what led to the historical — and somewhat incorrect — classification of diabetes being a coronary heart disease risk equivalent, which implies a 10-year ASCVD risk greater than 20% for every patient with diabetes. More contemporary data have shown otherwise.

Shubrook: Okay, that's important. We have a number that we could actually hang our hat on to identify the risk equivalent we're talking about. I think you've really highlighted that diabetes is an inflammatory vascular problem, but we see people across the spectrum of diabetes, and maybe that's an important factor.

I wanted to highlight that you had talked about the pathophysiology of type 2 diabetes. We often focus on the great majority of people with diabetes having type 2 diabetes, but that doesn't mean everyone does. When we talk about this, let's discuss our initial thoughts on type 2 and then we can talk about other types of diabetes.

Treating the Type 2 Diabetes Patient When CVD Is Not Apparent

Shubrook: How should I approach my patient with type 2 diabetes who doesn't have known cardiovascular disease?

Villalon: Such a conundrum. Such a question here. There is such heterogeneity in risk among type 2 and type 1 diabetes patients. This really poses a unique challenge to accurately risk-stratify and select appropriate preventive therapies.

Shubrook: I don't want people to leave today thinking that there is no cardiovascular risk. We know that one third of people with type 2 diabetes have a complication on the day they're diagnosed. We know that 25% of people who present with acute MI find out that they have diabetes at that time. I do think that there is an importance here and that we do need to risk-stratify our patients.

How should I risk-stratify them? What's the best calculator? The calculators are all a little bit different.

Villalon: All-encompassing. It starts with the pooled cohort equation, which factors in diabetes as one of the many risk factors for the development of either subclinical or clinical atherosclerotic cardiovascular disease. That's a wonderful tool. It is utilized for patients aged 40-75 years, and for me, it's a great starting tool.

Shubrook: I think you've highlighted some really important things. The great majority of our patients with type 2 diabetes will be between age 40 and 70. We are seeing so many people now diagnosed at a younger age with type 2 diabetes. What we've learned in the diabetes space is that the younger you're diagnosed with type 2 diabetes, the more progressive the disease is and the earlier you will succumb to complications if not aggressively treated.

One of the weaknesses of the current setting is related to knowing what to do with a 32-year-old who has had type 2 diabetes for 10 years. I can't use that same equation, so that's a challenge. Any suggestions?

Villalon: In my patient population, I have been utilizing more coronary artery calcium scans, or CAC scans. They really helped me with stratification among this, again, very heterogeneous group of people here. It has emerged as "the most sensitive noninvasive risk-stratification tool in this population."

We know that a score greater than zero is associated with a higher risk for coronary heart disease and events. We know that the absence of coronary artery calcium portends a very low absolute event rate. Notice how I did say very low — I did not say zero — because that does not mean no statin or other therapies such as aspirin, but it does help guide you in a narrow sliver of this population of patients.

Shubrook: That's great. Again, we need more tools to be able to really identify patients because diabetes is a relatively silent disease, as is heart disease.

One of the challenges that I have is looking at the type of diabetes as it relates to cardiovascular risk. I might be at fault here, but I really assume that the great majority of my patients with type 2 are at very high risk because of that early complication.

Type 1 vs Type 2 Diabetes Considerations

Shubrook: I struggle a little bit more with our type 1 patients in terms of how to identify their risk because it really is a different disease. We don't have insulin resistance. We don't have the same inflammatory markers. We do have hyperglycemia, but many of the risk calculators don't take that into account. When you see someone with type 1 diabetes, how do you handle that?

Villalon: At this point in time, Jay, I can't say I handle it any differently. I don't have any hard endpoints of results or trials to guide me there.

Shubrook: Yeah. That's an area where we should be doing some new research. I did find that for those with type 1, there is a much higher risk for mortality, which is largely driven by cardiovascular and renal complications. In many respects, this is just like type 2.

I was surprised to see that the duration of diabetes was not one of the biggest predictors. Age and hyperglycemia were bigger predictors. As I look at my patients with type 1, I might need to risk-stratify more actively by how old they are and how well they are controlled.

Let's say I have a person with type 1 who I'm worried about. Do I do all the same preventive treatments I would do for type 2?

Villalon: At this point, I think that's probably the right thing to do. The latest guidelines would be the 2018 AHA/ACC/AACVPR/AAPA/ABC/ACPM/ADA/AGS/APhA/ASPC/NLA/PCNA Guideline on the Management of Blood Cholesterol: Executive Summary: A Report of the American College of Cardiology/American Heart Association Task Force on Clinical Practice Guidelines. They state that moderate-intensity statin is indicated for those diabetic patients ages 40-75, irrespective of the risk or the pooled cohort equation. That does not answer the question of patients younger than 40, though.

Shubrook: At this point, we're back to practicing medicine and doing the best we can with seeing the patient in front of us and trying to estimate their risk.

It Takes Teamwork to Recognize and Address Coronary Event Symptoms

Shubrook: The other thing that I think is important to talk about is the clinical presentation of people with diabetes when they have an unstable coronary event. I remember being taught that you're more likely to have a silent event, but I think it's important for us not to lose the communication tools with our patients.

What do you share with your patients who have diabetes as to how they might experience an acute coronary event?

Villalon: As you were alluding to, Jay, I share with them the spectrum of symptoms, whether it be from the typical symptoms of angina, which should be chest discomfort. It could be outside of the chest as well as in the jaw, upper back, or shoulders, to fatigue and shortness of breath. Those very nondescript, nonspecific symptoms are also something I share. I usually tell people, "If it doesn't feel right to you, it doesn't feel right to me. Go seek medical attention."

Shubrook: I love that. I think that's important too. People know when they feel different. If they feel different, they should trust that and be cautious, especially when you have multiple chronic diseases.

Villalon: Absolutely.

Best Practices in Calculating CVD Risk and Optimizing Medication Usage

Shubrook: Let's talk a little bit about the nuts and bolts. I have a patient who is 48 years old. She has type 1 diabetes. It's been a long time. That duration maybe doesn't matter, but she's not been well controlled. Let's say that she reports exertional fatigue.

Of course, I'm going to send her to my local cardiologist. I want to make sure she gets an evaluation. What are the first couple of things you're going to do, and then, treatment wise, what are some of the things we should be thinking about for that person?

Villalon: After going through this ability, or lack thereof, of her diabetes control, I then would look at her blood pressure, weight, and activity level. I would have a glance at her lipid profile. Ideally, that lipid profile would also have others. It would have a lipoprotein(a), which helps me refine my estimate. It could also have apolipoprotein B, and possibly a high-sensitivity CRP (C-reactive protein).

All of these numbers, plus the symptoms, help me risk-stratify her in a more specific way. We're not at a time frame where we can attribute genome testing, but that's where I'd start with those labs.

Depending upon the severity or lack thereof, I'd ask if this is somebody whose symptoms I trust are due to angina — or not due to angina — and I'd ask myself if a functional or chemical stress test were appropriate.

If not, then I'd also ask myself and the patient if a coronary artery calcium scan would be appropriate. I think it all depends upon that patient presentation, and then, of course, at the very end of it and middle of it is the shared decision-making that is so important in this day and age.

Shubrook: I love that. You've taken us down a couple of pathways. If that patient had type 2 diabetes, and let's say that the workup was negative, as best we can tell with the information we have today, are there any special treatments that you would suggest, as a cardiologist, for the management of diabetes and cardiovascular disease?

Villalon: If the symptoms were very vague, and to me, not angina, but if I was concerned enough, given the history of diabetes — and we'll throw in that blood pressures were not controlled and maybe a family history of heart disease — then if the coronary artery calcium score were not zero, I'd absolutely entertain the shared decision-making of a baby aspirin and moderate- to high-intensity statin therapy for primary prevention.

Shubrook: I love that. Of course, now we have agents that treat diabetes that also help with heart disease. At least dulaglutide has some primary prevention. Of course, if she had a positive test or she actually had an MI, we have a plethora of SGLT2s and GLP-1s that we could be using that could really help with that.

Looking Ahead

Shubrook: I think there are some important things to take from today. I think you said that, first of all, the old dictum that diabetes is a cardiovascular risk equivalent is probably too generalized and not exactly true. We actually have a wider spectrum of people with diabetes, and we really need to take more of a nitty-gritty approach and use a pooled calculator that we can hang our hat on to estimate risk. So far, so good?

Villalon: Perfectly said, Jay.

Shubrook: Okay. You've said that we should be looking at additional factors that I would really highlight, particularly for type 1 diabetes. Look at other lipoproteins, look at the kind of measures of inflammation, because certainly the traditional diabetic dyslipidemia may not be present as we currently measure it in type 1 diabetes.

Of course, we have relatively new tools, like the coronary calcium score, that could really be quite helpful. Ultimately, at least in my primary care space, getting our patients who I'm worried about to the cardiologist is really important. I think anyone listening knows when they hear a story that they're uncomfortable or not sure what this is and they're worried about it, this is the time to call in and get some help.

Anything you would add to that?

Villalon: Not at all. In this day and age, it is not only the diabetologist and the family practitioner who are instituting at least these new classes of medications. It is the cardiologist and the group who should take the reins here. Just less than 5% of all active cardiologists feel comfortable prescribing medications for diabetes, and I think that number will change as we go forward.

Shubrook: Great point. Absolutely. Diabetes is a complex condition, it requires multiple touch points, and every one of our team members should be empowered to intervene to prevent complications. That includes using therapies that have been shown to reduce cardiovascular risk. I love that.

Thank you for joining us today, and thank you all for joining our topic.

Villalon: Thank you.

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