From EurekAlert!: "The muscles of elderly people and of people with type 2 diabetes contain lower concentrations of a protein known as PARL (short for 'presenilin-associated rhomboid-like'). PARL plays an important role within cells in remodeling power-generating mitochondria. It's PARL's job to oversee mitochondria's quality control, specifically by maintaining their integrity as the cellular components undergo normal processes of fission and fusion. The findings provide yet another link between insulin resistance and the function of mitochondria. ... When mitochondria aren't functioning properly, food doesn't get metabolized to the level that it should ... Instead of getting burned, fats accumulate in cells where they impair insulin's action. As mitochondria fail to work efficiently, they also produce more damaging free radicals. ... Relative to younger people, older people showed signs of insulin resistance. They also had fewer numbers of mitochondria and lower expression of the PARL gene. ... We hypothesize that impaired PARL function is an important risk factor for the development of insulin resistance in skeletal muscle by decreasing mitochondrial mass and energetics and increasing oxidative stress, thus contributing to impaired glucose metabolism. As insulin resistance continues to develop, mitochondrial function, oxidative damage, and PARL activity may decline further, leading to a vicious cycle that eventually contributes to the development of [diabetes] or other age-associated diseases, including sarcopenia."