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Purpose: Uncoupling protein 1 (UCP1) reduces mitochondrial production of reactive oxygen species (ROS). ROS overproduction is related to diabetic retinopathy (DR), a chronic complication of diabetes mellitus (DM). Therefore, deleterious polymorphisms in the UCP1 gene are candidate risk factors for DR. We investigated the relationships between the UCP1 -3826A/G polymorphism and risk of DR and UCP1 gene expression in human retina. Considering that superoxide dismutase-2 (MnSOD2) enzyme is the first line of defense against oxidative stress in mitochondria, we also analyzed MnSOD2 gene expression in retinal samples according to different UCP1 -3826A/G genotypes., Methods: In a case-control study, frequencies of -3826A/G polymorphisms were analyzed in 257 type 1 DM patients (154 cases with DR and 103 controls without DR). In a cross-sectional study comprising cadaveric cornea donors, UCP1 and MnSOD2 gene expressions were evaluated in 107 retinal samples differentiated according to different -3826A/G genotypes., Results: In the type 1 DM group, multivariate analysis confirmed that the G/G genotype was an independent risk factor for DR (OR = 3.503; P = 0.043). In cornea donors, G allele carriers had higher UCP1 cDNA and protein concentrations than A/A carriers (P = 0.034 and P = 0.039, respectively). Interestingly, G allele carriers exhibited increased MnSOD2 expression (P = 0.001)., Conclusions: This study suggests that the -3826A/G polymorphism is associated with DR in type 1 DM patients. This is the first report demonstrating UCP1 gene expression in human retinas and indicates that the -3826A/G polymorphism influences its expression. In addition, the -3826G allele was associated with increased MnSOD2 expression; thus, suggesting that this allele could be a marker of oxidative stress.

Background: In patients with type 2 diabetes, the presence of retinopathy is associated with increased cardiovascular disease, regardless of known risk factors for vascular disease., Objective: To investigate the association of diabetic retinopathy (DR) and its grades with the presence of subclinical coronary atherosclerosis in patients with type 1 diabetes., Methods: A cross-sectional study was conducted with 150 type 1 diabetes individuals asymptomatic for coronary artery disease. They underwent clinical evaluation for microvascular complications and for the presence of coronary artery calcification (CAC)., Results: Severe forms of DR (severe non-proliferative DR and proliferative DR) were associated with CAC (OR: 3.98 95% CI 1.13-13.9, p = 0.03), regardless of known risk factors for cardiovascular disease (age, A1C, hypertension, dyslipidemia and male gender)., Conclusion: Patients with severe forms of DR are at risk for the presence of coronary artery disease regardless of traditional cardiovascular risk factors.

Objective: To evaluate the prevalence of chronic vascular complications and associated factors in patients with type 1 diabetes mellitus (DM)., Methods: Cross sectional study with type 1 DM patients attending the Endocrine Division, Hospital de Clinicas de Porto Alegre. Patients were evaluated for presence of chronic vascular complications., Results: We evaluated 573 patients, mean age of 33 years. The presence of diabetic retinopathy (DR) was observed in 43.3%, diabetes duration [OR: 1.07, 95% CI: 1.03 to 1.11, P <0001], the presence of diabetic nephropathy (DN) [OR: 3.40; CI 95%: 1.89 to 6.13, P <0001] and hypertension (HPT) [OR: 2.12, 95% CI: 1.16 to 3.87, P = 0014] were associated with DR. The DN was present in 34.5% and was associated with HPT [OR: 1.93, 95% CI: 1.16 to 3.21, P = 0001] and total cholesterol [OR: 1.0, 95% CI: 1.0-1.01, P = 0.05]. Seven patients had macrovascular disease. Only 22% achieved an A1c of <7.0%. HPT was 33% and 48% had levels <130/80 mm Hg and 45% of patients had values for LDL> 100 mg/dl., Conclusion: We observed a high prevalence of microvascular complications and HPT. Duration of DM, HPT and presence of DN were associated with DR. HPT and dyslipidemia were associated with DN. Most patients did not meet the desired glycemic control, blood pressure and lipid targets. Greater efforts are needed to intensify the pressure and metabolic control of patients with type 1 DM.