The insulin-like peptide hormone INSL3, which is produced in men during puberty, plays an important role in the early prediction of certain diseases in adulthood. This is the conclusion reached by scientists from the University of Nottingham, whose article was published in Frontiers in Endocrinology. The hormone INSL3 is produced by the same cells in the testicles that produce testosterone. But testosterone levels fluctuate throughout a man's life and INSL3 levels remain constant from puberty onward, declining only slightly in old age. The scientists found that it could play a role as a prognostic biomarker for various age-related diseases, such as bone weakness, sexual dysfunction, diabetes and cardiovascular disease. The team analyzed blood samples from 3,000 men in two samples taken four years apart. The results showed that, unlike testosterone, INSL3 remains at a constant level, with each man's blood levels of the hormone being different. The discovery of the constant nature of this hormone is very important: It means that a man with high levels of INSL3 in his youth will also have high levels in his old age, making the man less prone to age-related diseases. Scientists speculate that the amount of the hormone is influenced by nutrition in childhood. In future studies, scientists plan to better investigate exactly what affects blood levels of the hormone.