Good blood glucose control characterizes patients without retinopathy after long diabetes duration

Diabetic retinopathy among Brazilian Xavante Indians

BACKGROUND

To describe the frequency of diabetic retinopathy (DR) and its associated variables in Brazilian Xavante Indians.

METHODS

A population-based survey carried out in two Xavante Reservations between 2008 and 2012, included 948 Indians aged 20 years or more, identified 246 individuals with type 2 diabetes. A non-probabilistic cluster sample of 140 diabetic individuals were submitted to ophthalmologic examination. Due to operational conditions and to optimize the field work, only the larger Xavante villages were included. Ophthalmologic examinations were performed during one trip to each reservation, in their villages and consisted of measurement visual acuity, anterior segment biomicroscopy, applanation tonometry, and direct and indirect ophthalmoscopy.

RESULTS

The frequency of DR was 19.3%, distributed as follows: mild non-proliferative retinopathy in nine (33.3%) subjects, moderate in nine (33.3%), severe in six (22.3%), very severe in two (7.4%), and high-risk proliferative DR in one (3.7%). The occurrence of DR was higher among those with a longer duration of diabetes, higher levels of glycated hemoglobin (HbA1c) and fasting glucose, papillary excavation ≥ 0.5, and among individuals in older age group. Using the log-binomial regression model, diabetes duration > 24 months and HbA1c ≥ 6.5% were significantly associated with the occurrence of DR.

CONCLUSIONS

The presence of DR (19.3%) in Xavante Indians is an alert for health care providers for this population, since diabetes is a new disease among them. Its association with disease duration, high levels of HbA1c and blood glucose calls attention for the necessity of more actions to improve diabetes control in this recently contacted ethnic group that needs particular attention.

Effect of polymorphisms of the MTHFR and APOE genes on susceptibility to diabetes and severity of diabetic retinopathy in Brazilian patients

Diabetes mellitus (DM) is a highly prevalent complex genetic disorder. There has been a worldwide effort in the identification of susceptibility genes for DM and its complications, and the 5-10-methylenetetrahydrofolate reductase (MTHFR) and apolipoprotein-E (APOE) genes have been considered good candidate susceptibility genes to this condition. The objectives of the present study were to determine if the 677T MTHFR and epsilon2/epsilon3/epsilon4 APOE alleles are risk factors for DM and for severity of diabetic retinopathy (DR). A total of 248 individuals were studied: 107 healthy individuals and 141 diabetic patients (46 with type 1 diabetes and 95 with type 2 diabetes), who also had DR (81 with non-proliferative DR and 60 with proliferative DR). The polymorphisms were analyzed by PCR followed by digestion with restriction enzyme or the single-nucleotide primer extension method. No evidence of association between the 677TT genotype of MTHFR gene and DM [cases: TT = 10/95 (10.6%); controls: TT = 14/107 (13%)] or with severity of DR was observed [cases: TT = 5/60 (8.5%); controls: TT = 9/81 (11.1%); P > 0.05]. We also did not find evidence of an association between APOE alleles and proliferative DR (epsilon2, epsilon3 and epsilon4 in cases: 9, 76, and 15%, and in controls: 5, 88, and 12%, respectively) but the carriers of epsilon2 allele were more frequent among patients with type 2 DM and DR than in controls [cases: 15/95 (15.8%); controls: 7/107 (6.5%); P < 0.05]. Therefore, our results suggest that the epsilon2 allele/APOE might be a risk factor for diabetes in the Brazilian population.

Development of proliferative retinopathy in patients with long-standing insulin-dependent diabetes mellitus

PURPOSE AND METHOD

Some patients with long-standing insulin-dependent diabetes mellitus (IDDM) develop little or no retinopathy. Using a clinic-based questionnaire and examination, we investigated a group of patients with over 40 years or more of IDDM who had been followed up at the King's Diabetes Centre for an average of 40 years. We compared those who had developed proliferative diabetic retinopathy during their disease with those with minimal or no retinopathy.

RESULTS

The study did not find any statistically significant differences between the two groups to suggest why some long-term insulin-dependent diabetics develop little retinopathy. Those who developed sight-threatening retinal complications did so at an average of 35 years after diagnosis and it resulted in little visual disablement. Very few patients in either group had developed other significant complications.

CONCLUSIONS

This study details an interesting group of patients with long-term IDDM mellitus with a mean follow-up period of 40 years. Some patients with long-standing IDDM develop little or no retinopathy. With the advent of community ophthalmic screening, these patients are now rarely seen in the eye clinic. Those who did develop retinal complications and required treatment have remarkably little visual disablement. However, these complications developed late in the history of their disease, emphasising the need for continued screening.

The temporal development of retinopathy and nephropathy in type 1 diabetes mellitus during 15 years diabetes duration

In this prospective study, the 10- and 15-year incidence and course of retinopathy were examined in relation to medical risk indicators from 3.1 +/- 1.9 (mean -/+ SD) years diabetes duration and onwards in 29 adult type 1 diabetic patients treated under routine care. A total of 28 patients were followed for 10 years and 20 patients for 15 years diabetes duration. After 10 years diabetes duration, 11 patients had developed any retinopathy (ten patients background retinopathy and one patient clinically-significant macular oedema). After 15 years diabetes duration, 16 patients had developed any retinopathy (12 patients developed background retinopathy and four patients developed potentially sight-threatening retinopathy, i.e. clinically significant macular oedema (n = 2) or severe non-proliferative retinopathy (n = 2)). None of the patients developed proliferative retinopathy. No differences were seen in mean HbA1c values between patients without any retinopathy and patients with background retinopathy, whereas patients who developed potentially sight-threatening retinopathy had higher mean HbA1c levels than patients without any retinopathy. Patients who developed potentially sight-threatening retinopathy had higher levels of mean HbA1c both after 10 (9.7 +/- 1.6 vs 6.9 +/- 1.5%; P < 0.05) and 15 years diabetes duration (9.3 +/- 1.2 vs 7.1 +/- 1.3%; P < 0.05), compared to patients without any retinopathy. They also had higher levels of mean HbA1c than patients with background retinopathy after 15 years diabetes duration (9.3 +/- 1.2 vs 7.7 +/- 1.1%; P < 0.05). There were no differences in blood pressure levels between patients who developed retinopathy and those who did not. Only two patients developed clinical signs of nephropathy (urinary albumin 320-1590 mg/l) after 12 and 13 years diabetes duration, respectively. At those time points, both patients had already developed background retinopathy since 2 years. In conclusion, the present study shows that the incidence of retinopathy is associated with the duration of diabetes and that there is a strong association between the degree of metabolic control and development of potentially sight-threatening retinopathy. The study also indicates that the development of retinopathy does not seem to be associated with hypertension or clinical signs of nephropathy.

Vascular leakage stimulates phenotype alteration in ocular cells, contributing to the pathology of proliferative vitreoretinopathy

Plasma leaking from damaged retinal blood vessels can have a significant impact on the pathologies of the posterior segment of the eye. Inflammation in the eye and metabolic change resulting from diabetes mellitus causes vascular leakage with alteration of the phenotype of retinal pigment epithelial (RPE) cells and fibrocytes, resulting in changes in cell function. Phenotypically altered cells then significantly contribute to the pathogenesis of retinopathies by being incorporated into tractional membranes in the vitreous, where they secrete matrix molecules, such as fibronectin, and express altered cell surface antigens. We hypothesize that there is a direct relationship between the leaking of plasma and the proliferation and phenotypic change of RPE cells and fibroblasts, thus exacerbating the pathology of retinal disease. If the hypothesis is correct, control of vascular leakage becomes an important target of therapy in proliferative vitreoretinopathy.

Glycemic control in patients with type I diabetes and normoalbuminuria after long diabetes duration

The importance of glycemic control for the avoidance of micro- and macroalbuminuria after a diabetes duration of 20 years or more was studied in type I (insulin-dependent) diabetic patients diagnosed before an age of 31 years. Glycemic control was assessed as glycated hemoglobin for 5 years or more, on average 9.8 years with 3.2 measurements per year. Of the 197 included patients, 97 men and 100 women, 112 were normoalbuminuric, 45 had microalbuminuria (20-200 mg/L), and 40 had macroalbuminuria (persistent albuminuria > 200 mg/L). Normoalbuminuric patients had a mean HbA1c +/- SEM for the whole measurement period of 6.9 +/- 0.08%, the microalbuminuric patients 7.3 +/- 0.14% (Mann-Whitney test versus normoalbuminuric group, p = 0.025), and macroalbuminuric patients 7.6 +/- 0.13 (p < 0.001). The patients were on average 45 years old, and had an age at onset of 14 years, without significant differences between the groups. Thirteen patients had regressed from macroalbuminuria to normo- (n = 6) or microalbuminuria (n = 7). Of the normoalbuminuric patients, 43% were male, compared to 44% with microalbuminuria and 73% with macroalbuminuria (chi 2, p = 0.026). Logistic regression, with absence of albuminuria as dependent variable, showed a beneficial impact from lower HbA1c and normal blood pressure (blood pressure < 140/90 mm Hg without antihypertensive treatment). In conclusion, these results suggests that absence of albuminuria after 20 years or more of diabetes is associated with lower HbA1c.