Waist size may flag higher metabolic risk in people with PWS
Patients had healthier glucose, lipid profiles than controls in small study
Written by |
Adults and children with Prader–Willi syndrome (PWS) had a favorable metabolic profile — a measure of how well the body processes energy — compared with controls in a small study from Bulgaria.
Still, people with PWS who had more abdominal fat, reflected by a higher waist circumference, had markers of higher blood pressure and metabolic risk that may predict cardiovascular problems later in life.
Waist circumference “could serve as a predictive marker for detecting higher metabolic risk,” the researchers wrote.
The study, “Metabolic profile in Prader-Willi syndrome patients followed at a single expert center of rare endocrine diseases,” was published in BMC Endocrine Disorders.
PWS can affect growth, appetite
PWS is typically marked by low muscle tone and poor growth in infancy, followed by intense hunger and a strong focus on food that starts in childhood. This can lead to overweight or obesity and related health problems.
“Worldwide medical studies emphasize the better metabolic profile of patients with PWS compared with non-syndromic obese patients or with obese controls,” the researchers wrote. This may be partly because people with PWS tend to accumulate more fat under the skin and less around internal organs, which is associated with worse health outcomes.
In this study, the researchers compared the metabolic profile of 25 people with a genetically confirmed diagnosis of PWS and 24 controls used as a comparison group. BMI matching was only partial. BMI is a ratio of weight and height commonly used as a proxy of body fat.
The average age was 11.3 years in both groups, but the age ranges differed. PWS participants ranged from about 3 months to 33 years old, while controls ranged from 3 to 16.5 years. Males made up 64% of the PWS group and 46% of the control group.
Most people with PWS (88%) were receiving growth hormone, a standard treatment for children with PWS that is known as somatropin (sold as Genotropin and Norditropin, with biosimilars available).
Among participants old enough to be classified by BMI, most people with PWS were overweight (19%) or had obesity (47.6%), and this was also the case in the control group (16.7% overweight and 70.8% with obesity). While people with PWS tended to have lower BMI and waist circumference than the controls, the differences were not statistically significant.
Patients show healthier glucose markers
Across the full study group, a larger waist circumference was significantly linked to higher systolic blood pressure. In the PWS group, a larger waist also was linked to higher systolic and diastolic blood pressure. Still, hypertension was more common in controls than in people with PWS.
People with PWS showed better glucose homeostasis, or better control of glucose (blood sugar). They had significantly lower blood levels of insulin, the hormone that helps glucose enter cells, and lower insulin resistance, which can occur when the body fails to respond properly to insulin.
Fasting hyperglycemia, meaning high glucose levels after not eating for at least eight hours, was similarly common in people with PWS and controls (16% vs. 16.7%).
Elevated blood levels of triglycerides, which are fatty molecules linked to risk of cardiovascular events, were found in three people with PWS (12%) and three controls (12.5%). Among participants with elevated triglycerides, those with PWS had higher blood levels of HDL cholesterol, a fatty molecule known as good cholesterol because it is thought to help protect the heart, than controls.
Separately, lower-than-normal HDL cholesterol levels were significantly less common among people with PWS compared with controls (12% vs. 25%).
People with PWS showed significantly lower blood levels of C-reactive protein (CRP; a marker of inflammation) and uric acid (a waste product), and significantly higher levels of sex hormone-binding globulin (SHBG) and adiponectin than controls. SHBG is a protein linked to metabolic health, and adiponectin is a hormone produced by fat tissue that helps protect against diabetes and heart disease.
Waist size tied to metabolic risk
Statistical analyses focused on people with PWS showed that a larger waist circumference was significantly linked to greater insulin resistance and higher blood levels of insulin, uric acid, CRP, and leptin, a hormone produced by fat cells that signals fullness.
These results suggest that more abdominal fat may be linked to worse metabolic risk factors.
At the same time, a larger waist circumference was significantly associated with lower blood levels of SHBG and adiponectin. Higher levels of HMW adiponectin were significantly linked to lower fasting blood glucose and lower systolic blood pressure.
Despite treatment with growth hormone, which is used to support growth and body composition in PWS, people with PWS who had body composition measurements had significantly lower height-adjusted bone mineral density, a measure related to bone strength, compared with obese controls who had the same measurements.
They also had significantly lower height-adjusted lean body mass, meaning less muscle tissue. Higher lean body mass was significantly associated with higher bone density, suggesting a link between muscle mass and bone health. The researchers noted the study was small and cross-sectional, and that BMI matching between groups was only partial.
“Patients with PWS have a favorable metabolic profile compared with healthy controls matched by age, sex, and BMI,” the researchers wrote. “These findings highlight the importance of routine metabolic and body composition assessment in the follow-up of patients with PWS and should be validated in larger, multicenter cohorts to better define predictive thresholds and clinical applicability.”
