In contrast, when an age-matched non-diabetes group was used for comparisons, diabetes patients displayed significant reductions in BMAL1, PER1 and PER3. As our study did not include an age-matched control group, we subdivided participants both with and without diabetes into a younger group (<50 years) and an older group (>50 years) to analyse mRNA levels. This evidence concerns the gene PER3 and diabetes mellitus.