Hofmann et al. investigated the rhythmic expression of clock genes and clock‐controlled genes in rat models with T1D including streptozotocin‐treated rats, spontaneous T1D LEW.1AR1‐iddm (lddm) rats and lddm rats used insulin for 10 days, and found that the clock genes all exhibited a rhythmic expression pattern while the expression of Bmal1, Per2, and Clock was altered in lddm and insulin‐treated lddm rats [125]. This evidence concerns the gene PER2 and type 1 diabetes mellitus.