Introduction. Type 2 diabetes (T2DM) has a slow onset and remains undiagnosed for years. This interval is estimated longer than 10 years, by extrapolating the correlation between known diabetes duration and prevalence of diabetic retinopathy (DR). However, those calculations were based upon weak assumptions: 1) that such correlation is linear, 2) any degree of DR was considered, including mild lesions observed in 10% of non diabetic individuals, 3) uncertain definition of T2DM, 4) time from onset of diabetes to appearance of DR arbitrarily set at 5 years. Purpose. To estimate the interval preceding diagnosis of T2DM after correcting the above assumptions Methods. 12,074 patients (35,545 screenings) were stratified into Younger-Onset (YO) if age at onset was <30 or Older-Onset (OO, ≥30) and currently on insulin treatment (IT) or not (NIT). DR was classified as mild or more severe (AnyDR) and moderate or more severe (Mod-DR). The best-fits between known duration of diabetes and prevalence of DR were calculated by the coefficient of determination (R2) and Akaike’s information criterion (AIC). Time preceding diagnosis of T2DM was estimated by adding the negative intercept on the horizontal axis of the best-fitting correlation line between known duration of OO-NIT and prevalence of DR to the positive intercept of the bestfitting correlation between duration of YO-IT and appearance of DR. Results. There were 7,298 OO-NIT (equivalent to T2DM), 1,719 with AnyDR and 685 with ModDR, and 1,725 YO-IT (equivalent to T1DM), 756 with AnyDR and 385 with ModDR. In the OO-NIT the best-fits were a quadratic model suggesting appearance of AnyDR 3.89 years before diagnosis of T2DM and a linear model with ModDR appearing 2.66 years before diagnosis. The onset of AnyDR following onset of YO-IT could not be timed, whereas a quadratic model suggested appearance of ModDR 3.29 years after its onset. The resulting estimate was (2.66+3.29) 5.95 years preceding T2DM diagnosis. Conclusions. Use of appropriate fitting models and stratification by treatment and DR severity lowers the estimate of unknown duration before diagnosis of T2DM to about 6 years, which is more realistic than previous estimates.

ESTIMATING THE INTERVAL PRECEDING DIAGNOSIS OF TYPE 2 DIABETES FROM THE TIME-COURSE OF RETINOPATHY PREVALENCE

PORTA, Massimo;DALMASSO, Paola
2013-01-01

Abstract

Introduction. Type 2 diabetes (T2DM) has a slow onset and remains undiagnosed for years. This interval is estimated longer than 10 years, by extrapolating the correlation between known diabetes duration and prevalence of diabetic retinopathy (DR). However, those calculations were based upon weak assumptions: 1) that such correlation is linear, 2) any degree of DR was considered, including mild lesions observed in 10% of non diabetic individuals, 3) uncertain definition of T2DM, 4) time from onset of diabetes to appearance of DR arbitrarily set at 5 years. Purpose. To estimate the interval preceding diagnosis of T2DM after correcting the above assumptions Methods. 12,074 patients (35,545 screenings) were stratified into Younger-Onset (YO) if age at onset was <30 or Older-Onset (OO, ≥30) and currently on insulin treatment (IT) or not (NIT). DR was classified as mild or more severe (AnyDR) and moderate or more severe (Mod-DR). The best-fits between known duration of diabetes and prevalence of DR were calculated by the coefficient of determination (R2) and Akaike’s information criterion (AIC). Time preceding diagnosis of T2DM was estimated by adding the negative intercept on the horizontal axis of the best-fitting correlation line between known duration of OO-NIT and prevalence of DR to the positive intercept of the bestfitting correlation between duration of YO-IT and appearance of DR. Results. There were 7,298 OO-NIT (equivalent to T2DM), 1,719 with AnyDR and 685 with ModDR, and 1,725 YO-IT (equivalent to T1DM), 756 with AnyDR and 385 with ModDR. In the OO-NIT the best-fits were a quadratic model suggesting appearance of AnyDR 3.89 years before diagnosis of T2DM and a linear model with ModDR appearing 2.66 years before diagnosis. The onset of AnyDR following onset of YO-IT could not be timed, whereas a quadratic model suggested appearance of ModDR 3.29 years after its onset. The resulting estimate was (2.66+3.29) 5.95 years preceding T2DM diagnosis. Conclusions. Use of appropriate fitting models and stratification by treatment and DR severity lowers the estimate of unknown duration before diagnosis of T2DM to about 6 years, which is more realistic than previous estimates.
2013
EASDec
Barcellona
23-25 May 2013
23
3
453
453
Diabetic Retinopathy
M. Porta; G. Curletto; E. Coppo; A. Raviolo; E. Sitia; S. Albani; P. Dalmasso
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/2318/139230
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