Macular recovery time in diabetic children without retinopathy

The aim of this study was to evaluate whether patients with initial diabetic nephropathy (defined as persistent microalbuminuria) have an impairment of macular recovery time and if this impairment changes in a long-term follow-up. Eighty insulin-dependent diabetic children without fluorescein angiographic signs of retinopathy and 80 controls were included in the study. All patients underwent nyctometry at the beginning of the study; diabetic children repeated the same test after 7 years. Diabetics were divided into two subgroups as regards presence of persistent microalbuminuria (albumin excretion rate > 20 micrograms/min/1.73 m2). At the beginning of the study, diabetics as a whole and normoalbuminuric patients showed similar data to controls, while microalbuminuric ones showed worse data at nyctometry (initial recovery time (IRT): 44.89 +/- 12.50; Summation method (SM): 509.1 +/- 312.0) in comparison with normoalbuminuric (IRT: 38.12 +/- 10.31, P = 0.010; SM 648.6 +/- 272.2, P = 0.036) and control subjects (IRT: 37.77 +/- 11.82, P = 0.004; SM: 661.5 +/- 297.5, P = 0.013). After 7 years, normoalbuminuric subjects showed a slight, but not significant worsening of nyctometry, while in microalbuminuric ones a significant difference between baseline and the end of follow-up was found (IRT: 44.89 +/- 12.50 vs. 52.91 +/- 13.9, P < 0.01; SM: 509.1 +/- 312.0 vs. 374.8 +/- 271.9, P < 0.05). Diabetic patients had a higher rate of abnormal IRT and SM than controls (P = 0.0004 and P = 0.0006, respectively). A higher number of patients in microalbuminuric subgroup than in normoalbuminuric one were found (both at baseline and at the end of follow-up) above the 95th centile of IRT (baseline 3 vs. 15; P = 0.0002; end of follow-up 5 vs. 23; P < 0.0001) and below the 5th centile of SM (baseline 5 vs. 14; P = 0.004; end of follow-up 5 vs. 19; P < 0.0001). Nyctometry was found more altered in microalbuminuric patients than in normoalbuminuric and controls. Unfortunately, there is a large overlap between the two diabetic subgroups and between diabetics and controls; for this reason, this technique is not suited for everyday practice.