Study links advanced PAH to diabetes

1 in 4 pulmonary arterial hypertension patients have diabetes, worse outcomes

Margarida Maia, PhD avatar

by Margarida Maia, PhD |

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Roughly one in four people with idiopathic (of unknown cause) pulmonary arterial hypertension (PAH) also have diabetes, a disease that causes high blood glucose (sugar), a multi-center Polish study found.

Having diabetes was linked to more advanced pulmonary vascular disease and worse survival, which held true even after accounting for age, body mass index (BMI), and presence of other cardiovascular (heart and blood vessel) diseases. 

The study, “Impact of diabetes mellitus on disease severity and patient survival in idiopathic pulmonary arterial hypertension: data from the Polish multicentre registry (BNP-PL),” was published in Cardiovascular Diabetology.

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PAH, or high pressure due to the narrowing of the small arteries that take blood from the heart to the lungs, can be the result of one of several causes, including genetic ones. When the cause is not known, it’s called idiopathic.

Earlier studies have found that people with idiopathic PAH have higher blood glucose and an abnormal lipid (fat) profile compared to the general population, and that it’s more common for them to develop diabetes.

While these metabolic changes are linked to the severity of the disease and can predict worse survival, not much is known about how diabetes affects the prognosis (outlook) of idiopathic PAH.

To know more, a team of researchers in Poland drew on data from people who were registered in the Database of Pulmonary Hypertension in the Polish Population (BNP‑PL). The data were collected from March 2018 to August 2020.

Of the 532 adults with idiopathic PAH in the database, 136 (25.6%) had diabetes. On average, they were a mean 14 years older than those who didn’t have diabetes (70.4 vs. 56.4 years). They also had significantly  higher BMI, a measure of body fat (29.7 vs. 25.7).

More functional limitations

Having diabetes also was linked to more functional limitations. This was evaluated using the World Health Organization (WHO) functional classification, where a higher class indicates more severe disease.

WHO functional class III or IV were more common among people with diabetes than among those without diabetes (75% vs. 44%). In contrast, class I or II, meaning mild or no shortness of breath with physical activity, were not as common (25% vs. 56%).

Moreover, those with diabetes had significantly poorer exercise tolerance, as indicated by a shorter distance covered in the 6-minute walking distance test (6MWDT), 301 vs. 423 meters (or 329 vs. 472 yards).

Blood levels of NT‐proBNP, a marker of heart failure, were significantly higher in PAH patients with diabetes (1,628 vs. 461 picograms per milliliter). Their heart’s right upper chamber (atrium) was larger (26 vs. 22 square centimeters). This measure reflects the function of the right ventricle that pumps blood to the lungs and is associated with clinical outcomes in pulmonary hypertension.

Right heart catheterization, an invasive test that allows doctors to measure blood pressure in the pulmonary arteries, revealed a higher mean pressure in the heart’s right atrium and pulmonary artery in people with diabetes compared with those without diabetes.

Over a mean follow-up period of 21 months, there were 122 (22.9%) deaths. Having diabetes was linked to a 2.46 times greater risk of death. Besides diabetes, other predictors of death were age, distance covered in the 6MWDT, and pressure in the heart’s right atrium.

Propensity score matching

To ensure a fair comparison, the researchers used propensity score matching to match people in the two groups. After matching, 136 pairs of people with or without diabetes were compared. However, the observations remained the same even after matching.

People who have both idiopathic PAH and diabetes “have more advanced pulmonary vascular disease and worse survival than those without [diabetes],” the researchers concluded.

“Importantly, these findings remain significant even after accounting for age, BMI, and associated cardiovascular comorbidities [coexisting diseases] and treatments,” they added.

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