A 5-year follow-up study on the incidence of retinopathy in type 1 diabetes mellitus in relation to medical risk indicators

HbA1c levels in children with type 1 diabetes and correlation to diabetic retinopathy

BACKGROUND

Type 1 diabetes mellitus (T1D) is a metabolic disease causing hyperglycemia due to β-cell destruction. Despite adequate treatment, complications such as diabetic retinopathy (DR) are common. The first aim was to investigate if acute onset of type 1 diabetes differed between those who had developed retinopathy and who had not after 15 years from diagnosis. The second aim was to investigate if mean glycosylated hemoglobin (HbA1c) levels affect the time to development of DR.

METHODS

The medical records of all children and adolescents diagnosed with type 1 diabetes during 1993-2001 in our area in Sweden were studied retrospectively and the mean HbA1c each year until the development of retinopathy was investigated. In total 72 patients were included and the follow-up time was between 15 and 23 years. Gender, p-glucose, age and HbA1c at diagnosis were analyzed for possible correlations to years to retinopathy.

RESULTS

HbA1c was significantly higher among those who had developed DR after 15 years from diagnosis, 98±9.2 (n=25) vs. 86±9.2 (n=46; p=0.025). A negative correlation was found between age at diagnosis and years to DR (rs=-0.376; p=0.026). Mean HbA1c levels at years 6-10 after diabetes diagnosis correlated significantly (rs=-0.354, p=0.037) to years until retinopathy. Mean HbA1c levels at years 1-15 after diabetes diagnosis were significantly higher at years 2-3 and years 5-8 for those who had developed retinopathy after 15 years from diagnosis.

CONCLUSIONS

Higher HbA1c levels shortened the time to development of retinopathy. It is therefore important to keep HbA1c as close to normal as possible.

Epidemiology of diabetic retinopathy and macular oedema: a systematic review

AIMS

To systematically review the literature on the prevalence and incidence of diabetic retinopathy (DR) and macular oedema (MO).

METHODS

A search of the bibliographic databases (Medline, Embase, CINAHL) was conducted up to October 2001. Selected relevant studies were scrutinized and included in the review.

RESULTS

A total of 359 studies were included. The studies were reported in nearly 100 different journals and in over 50 countries. The majority of the studies were US-based, with large studies such as the Wisconsin Epidemiologic Study of Diabetic Retinopathy dominating the literature. The studies were quite dated and highly heterogeneous in nature in terms of patient selection with variable inclusion criteria (age range, gender, diabetes duration and type, ethnicity, comorbidity, and DR status, assessment, and classification).

CONCLUSIONS

There are inconsistencies between epidemiological studies, and differences in study methods may contribute to conflicting reports of prevalence and incidence of DR and MO in diabetic populations. As new therapies for DR and its associated complications emerge, the need to capture and monitor new epidemiological data becomes increasingly important to be able to assess the impact and effectiveness of these therapies. Robust, longitudinal capture of patient data is, therefore, essential to evaluate the impact of current practice on the epidemiology of diabetic eye complications.

Incidence of sight-threatening retinopathy in Type 1 diabetes in a systematic screening programme

AIM

To measure the cumulative incidence of any retinopathy, maculopathy and sight-threatening diabetic retinopathy (STDR), and calculate optimal screening intervals by retinopathy grade at baseline for patients with Type 1 diabetes attending an established systematic retinal screening programme.

METHODS

All patients with Type 1 diabetes registered with enrolled general practitioners, excluding only those attending an ophthalmologist, were studied if retinopathy data was available at baseline and at least one further screen event. Screening utilized non-stereoscopic 3-field mydriatic photography and modified Wisconsin grading. STDR was defined as moderate pre-proliferative retinopathy or greater and/or significant maculopathy in any eye.

RESULTS

Patients (n=501) underwent 2742 screen events. Cumulative incidence of STDR in patients without baseline retinopathy was 0.3% (95% CI 0.0-0.9) at 1 year, rising to 3.9% (1.4-5.4) at 5 years. Rates of progression to STDR in patients with background and mild pre-proliferative retinopathy at 1 year were 3.6% (0.5-6.6) and 13.5% (4.2-22.7), respectively. Progression to STDR was greater in patients with a higher grade of baseline retinopathy (P=0.001) or a longer disease duration (P=0.003). For a 95% likelihood of remaining free of STDR, mean screening intervals by baseline status were: no retinopathy 5.7 (95% CI 3.5-7.6) years, background 1.3 (0.4-2.0) years and mild pre-proliferative 0.4 (0-0.8) years.

CONCLUSIONS

Screening at 2-3 year intervals, rather than annually, for patients without retinopathy in Type 1 diabetes is feasible because of the low risk of progression to STDR, and may result in significant cost savings for a screening programme. Patients with higher grades of retinopathy require screening at least annually or more frequent.

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.

Progressive proliferative diabetic retinopathy after transplantation of the pancreas. A case and a review of the topic

The unusual case history of the development of a progressive diabetic retinopathy despite normal blood glucose after transplantation of the pancreas and despite panretinal laser coagulations is described. A 26-year-old male with diabetic background retinopathy underwent a segmental transplantation of the pancreas in 1988. One year after surgery, a progressive proliferative retinopathy despite normoglycemia was found, which required an intensive panretinal photocoagulation during the following months. However, despite massive retinal coagulations, vitreous hemorrhages and retinal neovascularizations continuously occurred, thus requiring two vitrectomies. After these procedures, visual acuity recovered distinctly. It is suggested that the 'point of no return' for the development of proliferative changes in the retina had been passed at a time when a background retinopathy was still present. The effect of normoglycemia during follow-up of patients with diabetic retinopathy, described in the literature, is compared to this unusual case history.