Objective: The renal and retinal vasculature shares similar pathophysiologic features. Retinal vasculature changes, even without typical retinopathy, can predict microvascular disease in type 1 diabetes (T1D). We hypothesise that peripheral retinal vessels are wider and predict incident renal dysfunction in adolescents with T1D.
Research Design and Methods: In this longitudinal study of 441 retinopathy free and normoalbuminuric adolescents with T1D retinal photographs were measured by computer software (Singapore I Vessel Assessment) with vessel calibres summarized in the standard “central zone” [Central Retinal Arterial and venular equivalents (CRAE and CRVE respectively)] and “extended zone” [Mean width of arterioles and venules (MWa and MWv)]. Retinal vascular geometry including length diameter ratio (LDR) and simple tortuosity (ST) was quantified. Generalised estimating equation was used to explore associations between vessel calibres, LDR, ST and incident renal dysfunction. Incident renal dysfunction was defined as Albumin excretion rate (AER) > 7.5µg/min, with results expressed as odds ratio (OR) and 95% CI.
Results: Mean ± SD age was 14.1±1.5 year, median diabetes duration 4.8 year [IQR 3.3, 7.5], A1C 8.4 ±1.3% (IFCC 68 ±14.2mmol/mol). Incident renal dysfunction occurred in 186/441 (42%) over a median 4 year follow-up. Wider MWa and MWv (4th vs. 1st quartile), higher LDR (4th vs. 1st -3rd quartile) and lower ST (1st vs. 2nd-4th quartile) were associated with renal dysfunction: MWa OR 2.0 (1.2, 3.5); MWv 2.2 (1.3, 3.6), LDRa 1.5(1.07, 2.08), LDRv 1.4 (1.02, 1.9), STa 1.5(1.1, 2.2), STv 1.4 (1.1, 1.8) after adjusting for covariates (A1C, diabetes duration, gender, height and blood pressure). Central vessels were not related to renal dysfunction: CRAE: 0.9 (0.5, 1.5); CRVE: 1.3 (0.8, 2.1), all p<0.05.
Conclusions: We speculate that small vessel dilatation and tortuosity are modulators of diabetic renal disease.
V. Velayutham: None. M.E. Craig: None. G. Liew: None. T.Y. Wong: None. A. Jenkins: Research Support; Self; Medtronic, Mylan, Sanofi-Aventis. K.C. Donaghue: None.