The Relationships between Retinopathy and Other Vascular Complications in Adults with Long-Standing Diabetes—Results from the Canadian Study of Longevity in Type 1 Diabetes (T1D)

We aimed to measure the prevalence of retinopathy in a T1D cohort of 75 adults with T1D duration of ≥50 years, and to determine association with other vascular complications. Participants underwent ultra-widefield retinal imaging and optimal coherence tomography. Neuropathy was characterized by electrophysiology and corneal confocal microscopy. Intrarenal hemodynamic function was determined by inulin and para-aminohippurate clearance, and arterial stiffness was measured by applanation tonometry, both at baseline and in responses to intravenous angiotensin II (ANGII). Participants were classified as having no diabetic retinopathy (ⱷDR), non-proliferative (NPDR), or proliferative (PDR), and associations were determined using multivariable linear regression adjusting for age, sex, and HbA1c. Thirty-nine (52%) participants had PDR, 24 (32%) had NPDR, and 12 (16%) had ⱷDR. Those without retinopathy had lower HbA1c vs. those with NDPR and PDR (6.7±0.6% vs. 7.4±0.7% and 7.5±0.9%, p=0.019). PDR was associated with lower corneal nerve fibre density, worse electrophysiology, and a greater number of signs and symptoms of neuropathy, but not with intrarenal hemodynamic function. Retinopathy severity was associated with greater response to ANGII for carotid-radial pulse wave velocity (mean change -4.9±11.4% vs. 8.2±18.5% vs. 12.9±20.2% for ⱷDR, NPDR, and PDR respectively, p=0.043). In longstanding T1D, retinopathy associated strongly with neuropathy and arterial stiffening, but not with renal hemodynamic function. Greater understanding of the co-occurrence of microvascular complications in patients with T1D, and relationships with macrovascular abnormalities such as arterial stiffness, may improve early detection and management of diabetes-related diseases.