COMMENTARY

From Naysayer to Convert: Cardiologists Should Prescribe SGLT2 Inhibitors

Melissa Walton-Shirley, MD

Disclosures

September 05, 2019

Cardiologists have largely resisted calls to get more involved in diabetes. The comments on the Medscape article "Cardiologists Must Get Up to Speed on Treating Diabetes" echoed the sentiments of many regarding sodium-glucose contransporter-2 (SGLT2) prescribing.  Among the choice complaints: "Quite frankly I believe primary care physicians should step up to the plate." "Cardiologists are not diabetologists." "Not a chance. Cardiologists have enough on our plate."

I used to agree, but now I wonder if perhaps cardiologists need to get a bigger plate. 

The DAPA-HF trial presented at the European Society of Cardiology (ESC) Congress demonstrated an 18% reduction in cardiovascular mortality in patients with a left ventricular ejection fraction at or below 40%. With a number needed to treat of 21, there should be little hesitation for cardiologists to prescribe the SGLT2 inhibitors. Any new drug must muscle its way past the obstacles of prior authorization and affordability. But this newer drug class must also overcome preconceived notions that a "diabetes drug" does not belong on a cardiologist's prescription pad. Then there is the "getting to know you" period for side effects, dosing, and monitoring that every new drug demands.

During his talk, "Integrating SGLT2 Inhibitors in Diabetes Treatment: A Guide for Cardiologists," Naveed Sattar, a professor of metabolic medicine from the University of Glasgow, emphasized that "these drugs are not just diabetes drugs."

I sat down with him for a Q&A  on how we cardiologists might embrace this new era of diabetes management. 

Dr Naveed Sattar

Should cardiologists take the lead in monitoring and treating type 2 diabetes in their coronary artery disease patients?

If you mean in terms of looking for new type 2 diabetes in their patients, they should be doing that anyway. A hemoglobin A1c (HbA1c) test in the nonfasting or the fasting patient, regardless of whether the patient is sick or not, allows cardiologists to diagnose diabetes quite easily in many settings, including ACS [acute coronary syndrome], the secondary care clinic, or even on the ward. If the patients haven't been tested before or not for a long time, cardiologists will find a proportion with undiagnosed diabetes.

This might seem a simple question, but what is your definition of diabetes?

If the HbA1c is above 6.5%. That's diabetes.

I've always told my patients that diabetes is like pregnancy: There no such thing as "borderline pregnant." How do you approach a patient who had a myocardial infarction (MI) and has an HbA1c of 6.2%, for instance?

At that moment, they aren't considered diabetic and do not warrant treatment with drugs. What they do warrant is emphasis on lifestyle and weight loss to stop them from progressing.

How should cardiologists talk to their patients with diabetes about SGLT2 inhibitors?

This is how I would approach it: "Ms. Smith, you have diabetes. We treated your MI, and now we have a new class of drugs that will help your sugar levels, decrease your risk of having another heart attack or of developing heart failure, and it could benefit your kidneys. By the way, it can help you lose weight and your blood pressure might come down too. I think it would be good for you. But it can increase genital infection risk. Urinary hygiene is important: for instance, washing your hands, bathing regularly, and observing good toileting habits. There is a proportion of patients who get genital infections, which we can treat."

I also tell them it's important to observe sick day rules, such that you don't take your meds when you aren't eating well.

What are the potential pitfalls of prescribing this class of drugs? I think we are fearful that we might induce hypoglycemia or other side effects.

The evidence indicates this class of drugs does not induce sugar levels to go too low. They work by helping the kidney get rid of excess sugar.

Is there any role now for metformin as a first-line therapy in the patient with coronary heart disease and diabetes?

The new ESC guidelines[1] say that if a patient has diabetes and coronary artery disease, and is not on metformin, we should start them on an SGLT2 inhibitor based on the evidence. If you start metformin first, we don't know if it will prevent events in those who already have heart disease. If you start it at the same time, you are adding two more drugs to the patient.

Metformin is a brilliant drug. It's very cheap. It promotes weight loss, but one in five have GI [gastrointestinal] side effects, and if you start two drugs at the same time, it can lead to loss of confidence in both drugs so the patient stops taking both. It makes sense just to start one of these newer drugs.

Some older diabetes medications are not associated with lower mortality despite their ability to reduce HbA1c levels. Should we use a different marker to measure successful diabetes management?

The answer at this moment in time is no. NTproBNP [N-terminal pro B-type natriuretic peptide] is a little better in some, but I would not recommend widespread use of NTproBNP. If we know the patients are taking an SGLT2i, we know they get the benefit.

We give lots of drugs that work that don't have a [measurable serum] biomarker. For β-blockers, it's perhaps heart rate. We give aspirin but we don't use the bleeding test. Weight loss and BP [blood pressure] reduction perhaps are good indicators that [the SGLT2i is working].

Many of us don't have recent training on the management of diabetes. What do you suggest?

A relatively simple program could be designed to give the majority of cardiologists a degree of confidence and some extra assuredness that they aren't going to harm. They should also liaison with PCPs [primary care physicians] and endocrinologists. I work in cardiometabolic medicine. The UK has that training program.  

What do you think of Robert Eckel's (incoming president of the American Diabetes Association) recommendation for a new subspecialty in the US that bridges cardiology and diabetes ?

It would be simpler to provide diabetes modules for cardiologists that allows them to prescribe the drugs safely so our patients can benefit.

This is something that cardiologists can no longer neglect. These drugs must be a part of their menu. There is no reason that cardiologists should not take the lead in prescribing them. If they are not comfortable, they should liaise with the diabetic specialist or PCP and make a referral.

My Takeaway From the Q&A

Professor Sattar makes a strong case for cardiologists to do more in diabetes management. I am sympathetic to the excuse that we are too busy, but we have changed our prescribing patterns more significantly than most specialties in the last two decades (save the oncologists). We select direct-acting oral anticoagulants for our patients with atrial fibrillation. We spend time fighting for our patients to receive proprotein convertase subtilisin/kexin type 9 inhibitors. We are still getting to know the angiotensin receptor-neprilysin inhibitor for heart failure.

In light of all the plates we have spinning, should cardiologists take on just one more thing?  

I believe it's time to start thinking of the SGLT2i drug class, not as a diabetes drug with a side benefit of reduced CV mortality[2,]but perhaps as a cardiac med with the side benefit of improved HbA1c and renal protection.[4] 

Naveen Sattar reports consulting for Amgen, AstraZeneca, Boehringer Ingelheim, Eli Lilly, Napp Pharmaceuticals, Novo Nordisk, and Sanofi and research grants from Boehringer Ingelheim.

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