AIMS/HYPOTHESIS: Glucose metabolism marks health and disease and is causally inferred in the aging process. Ambulant continuous glucose monitoring provides 24-hour glucose rhythms under daily-life conditions. We aimed to describe ambulant 24-hour glucose rhythms measured under daily-life condition in relation to calendar and biological age in apparently healthy individuals. METHODS: In the general population and families with propensity for longevity, we studied parameters from 24-hour glucose rhythms; glucose levels and its variability, obtained by continuous glucose monitoring. Participants were 21 young (aged 22 to 37 years), 37 middle-aged (aged 44 to 72 years) individuals from the general population, and 26 middle-aged (aged 52 to 74 years) individuals with propensity for longevity. All were free of diabetes. RESULTS: Compared to young individuals, middle-aged individuals from the general population had higher mean glucose levels (5.3 vs 4.7 mmol/L, p <0.001), both diurnally (p <0.001) and nocturnally (p = 0.002). Glucose variability was higher in the middle-aged compared to the young (standard deviation 0.70 vs 0.57 mmol/L, p = 0.025). Compared to middle-aged individuals from the general population, middle-aged individuals with propensity for longevity had lower overall mean glucose levels (5.2 vs 5.4 mmol/L, p = 0.047), which were more different nocturnally (4.8 vs 5.2 mmol/L, p = 0.003) than diurnally (5.3 vs 5.5 mmol/L, p = 0.14). There were no differences in glucose variability between these groups. Results were independent of body mass index. CONCLUSIONS: Among individuals without diabetes, we observed significantly different 24-hour glucose rhythms depending on calendar and biological age. © 2012 The Authors Aging Cell © 2012 Blackwell Publishing Ltd/Anatomical Society of Great Britain and Ireland.