Calorie restriction increases insulin sensitivity to promote beta cell homeostasis and longevity.

Caloric restriction (CR) extends organismal life- and health-span by improving glucose homeostasis. How CR affect the structure-function of pancreatic beta cells remains unknown. We used single nucleus transcriptomics to show that CR increases the expression of genes for beta cell identity, protein processing, and organelle homeostasis. Gene regulatory network analysis reveal that CR activates transcription factors important for beta cell identity and homeostasis, while imaging metabolomics demonstrates that CR beta cells are more energetically competent. In fact, high-resolution microscopy show that CR reduces beta cell mitophagy to increase mitochondria mass and the potential for ATP generation. However, CR beta cells have impaired adaptive pro liferation in response to high fat diet feeding. Finally, we show that long-term CR delays the onset of beta cell aging and promotes cell longevity by reducing beta cell turnover. Therefore, CR could be a feasible approach to preserve compromised beta cell structure-function during aging and diabetes. 27 diabetes. Overall design: Pancreatic islets were isolated from mice on ad-libitum diet (AL), 20% caloric restriction (CR) or 60% high-fat diet (HF) for 2 or 12 months. Islets were snap-frozen immediately. Single nuclei were isolated from snap-frozen isolated islet pellets and were processed for transposition, barcoding, library construction and sequencing according to 10x Genomics Guidelines for Single Cell Multiome ATAC + Gene Expression.