Onset of NIDDM occurs at least 4-7 yr before clinical diagnosis.
Level 4 - case-series / case-control
Cross-sectional observational study using regression-based extrapolation
PubMed 1516497 · doi:10.2337/diacare.15.7.815
What was done
Researchers evaluated two population-based cohorts of white individuals with non-insulin-dependent diabetes mellitus (NIDDM) in the United States and Australia. They measured the prevalence of diabetic retinopathy and the duration of diabetes following clinical diagnosis. Weighted linear regression was used to model the relationship between diabetes duration and retinopathy prevalence and to extrapolate back to zero prevalence.
What was found
Prevalence of retinopathy at clinical diagnosis was estimated at 20.8% in the United States and 9.9% in Australia, increasing linearly with duration of diabetes. Back-extrapolation indicated that detectable retinopathy began approximately 4 to 7 years before clinical diagnosis. Accounting for external data suggesting diabetes is present 5 years before retinopathy becomes detectable, the onset of NIDDM was estimated to occur 9 to 12 years prior to clinical diagnosis.
Why it matters
This paper demonstrates that type 2 diabetes often remains clinically unrecognized for up to a decade, during which microvascular complications actively develop without intervention.
Limits
The abstract does not report the total sample size (n). The study population was restricted to white patients in two countries. Findings rely on linear back-extrapolation and external assumptions regarding preclinical disease timelines rather than direct prospective longitudinal screening.
Cited by
- supports Patients with diabetes typically experience a 5- to 7-year delay before receiving a formal diagnosis.