BackgroundThis meta-analysis was conducted given the contradictory findings from studies on the influence of diabetes duration or age at onset on mortality in patients with insulin-dependent diabetes mellitus (IDDM).MethodsElectronic databases (PubMed, Embase, Cochrane, Web of Knowledge, Scopus, and CINHAL) were comprehensively searched to identify relevant studies until October 31, 2022. All of the selected articles contained statistics on hazard ratios, relative risks (RRs), or odds ratios, or data for estimating the association between diabetes duration or age at onset and total mortality in IDDM patients. Regardless the heterogeneity assessed by the I2statistic, pooled RRs and 95% confidence intervals (CI) for total mortality were acquired via random effect meta-analysis with inverse variance weighting.ResultsThis meta-analysis finally included 19 studies involving 122, 842 individuals. Both age at onset and diabetes duration were positively associated with an increased mortality rate in IDDM patients. Specifically, the pooled RRs for age at onset and diabetes duration were 1.89 (95%CI 1.43–2.50) and 1.89 (95%CI 1.16–3.09) respectively. Subgroup analyses revealed that only prepubertal onset was associated with a greater survival advantage than pubertal or postpubertal onset.ConclusionsThe findings of this meta-analysis and systematic review suggest that a later age at onset or longer diabetes duration is associated with increased risk of total mortality in IDDM patients. However, this conclusion shall be interpreted with caution due to the possibility of residual confounding and be confirmed in the future by well-designed studies.Supplementary InformationThe online version contains supplementary material available at 10.1186/s13098-023-01113-x.