Glucose tolerance screenings should start at age 5: Researchers

Meta-analysis showed earlier screening may lead to better health outcomes

Margarida Maia, PhD avatar

by Margarida Maia, PhD |

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Abnormal glucose tolerance is common in young cystic fibrosis (CF) patients. Early screening, starting at the age of 5, may lead to better health outcomes by making it possible to intervene early, a meta-analysis study found.

“Abnormal glucose tolerance affects every third child” and “every second adult” with CF, a team of researchers in Hungary wrote, urging “regular screening … should be started at 5 years of age.”

The study, “Early onset of abnormal glucose tolerance in patients with cystic fibrosis: A systematic review and meta-analysis,” was published in the Journal of Cystic Fibrosis.

In CF, damage to the pancreas causes problems with insulin, a hormone that controls the levels of glucose (sugar) in the blood by helping it move into cells, where it’s used for energy. As a result, many patients develop what’s known as CF-related diabetes (CFRD).

Many patients don’t know they have CF-related diabetes until they are diagnosed. For this reason, guidelines recommend patients be tested every year with an oral glucose tolerance test, starting at age 10, to find out if they have abnormal glucose tolerance.

Data suggest abnormal glucose tolerance, or impaired ability to dispose of a glucose load, can begin earlier in life. With screening starting at age 10, doctors may be “missing the opportunity for early detection and intervention,” the researchers wrote.

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Data from more than 520,000 CP patients part of analysis

To better understand this, they analyzed data from 457 studies involving more than 520,000 CF patients. Compared with healthy individuals, CF patients had nearly five times higher odds of diabetes and 10 times higher odds of abnormal glucose tolerance.

CF-related diabetes was more common in adults than in children (27% vs. 9%). The proportion of children and adolescents with CF-related diabetes tended to increase with age, from 0.5% at 0-5 years old to 5% at 5-10 years old. In the 10-18 year range, the proportion was 11%.

“The risk of CFRD increases throughout life, with the most rapid increase observed during adolescence. This increase starts early in life, before the age of 10, and plateaus by adulthood,” the researchers wrote.

The proportion of adults with abnormal glucose tolerance also was higher than that of children (51% vs. 31%). Every third child with CF had abnormal glucose tolerance, with no significant differences among age groups.

However, in the 5-10 year range, the proportion of children with abnormal glucose tolerance was as high as 42%. Based on these findings, the researchers recommend starting oral glucose tolerance test at the age of 5, instead of waiting until the age of 10.

Children with pancreatic exocrine insufficiency, which occurs when the pancreas fails to release enough enzymes to break down food, had about twice the risk of having abnormal glucose tolerance.

In adults and children with two copies of F508del, the most common CF-causing mutation, the risk of CFRD was up to 69% higher compared with adults and children carrying other disease-causing mutations.

“In this comprehensive and gap-filling meta-analysis, we have shown that AGT is not only more prevalent in [CF patients] compared to controls, but also affects a higher proportion of the young age group than hitherto estimated,” the researchers wrote. “Our findings also support the scientific hypothesis that AGT is a spectrum disease that manifests as prediabetes in very early childhood, and progresses to CFRD over time.”

Prediabetes is when blood glucose levels are higher than normal, but not high enough yet to be diagnosed as diabetes. In this meta-analysis, a type of study that pools data from multiple individual studies, the proportion of CF patients with prediabetes was similar in adults (19%) and children (14%).

“Prediabetes frequently presents before 10 years of age. Our study suggests considering earlier AGT screening, starting from 5 years of age,” the researchers concluded, noting the need “for additional research for guideline adjustments and provides the opportunity for early intervention.”