Mitochondrial cristae density is increased following high‑intensity interval training in men with type 2 diabetes – published online 08/03/2026

Martin E. de Almeida, Niels Ørtenblad, Amalie B. Platz, Maria H. Petersen, Kurt Højlund, Joachim Nielsen

Mitochondrial cristae are folds of the inner membrane essential for oxidative phosphorylation (ATP production). While mitochondrial dysfunction is a hallmark of type 2 diabetes, it remains unclear whether cristae density is altered in this condition and whether it can be modified by exercise. In this issue, de Almeida et al (https://doi.org/10.1007/s00125-026-06694-6) quantify mitochondrial cristae density in human skeletal muscle, analysing thousands of mitochondria with high precision, and show that 8 weeks of high-intensity interval training (HIIT) increases cristae density. This adaptation expands the inner mitochondrial membrane surface available for energy conversion. Importantly, the increase in cristae density was also observed in men with type 2 diabetes, indicating that the capacity for mitochondrial remodelling is preserved despite metabolic disease. The authors conclude that these findings provide evidence of structural mitochondrial plasticity in humans, reveal an unrecognised site of mitochondrial regulation by exercise, and support HIIT as a stimulus to improve muscle oxidative capacity in type 2 diabetes.