Elsevier

Journal of Diabetes and its Complications

Volume 26, Issue 6, November–December 2012, Pages 506-512
Journal of Diabetes and its Complications

Relationship between diabetic retinopathy, microalbuminuria and overt nephropathy, and twenty-year incidence follow-up of a sample of type 1 diabetic patients,☆☆,

https://doi.org/10.1016/j.jdiacomp.2012.06.010Get rights and content

Abstract

Purpose

To determine the incidence and relationship of diabetic retinopathy (DR), microalbuminuria and overt nephropathy (ON).

Method

A 20-year prospective study, in a cohort of 110 consecutive type 1 diabetes mellitus (DM) patients, without diabetic retinopathy or microalbuminuria at enrolment in 1990.

Results

The 20-year incidence of any DR was 70.91%, microalbuminuria 42.72%, and ON was 23.63%. Regarding the risk factors: pre pubertal age at diagnosis was significant for DR and ON, LDL-cholesterol and CT/HDL-cholesterol were significant for DR but not for microalbuminuria or ON. The relationship between DR and ON demonstrated that DR was a significant risk factor for ON, but ON was significant for sight-threatening DR. At the end of the study, two major groups of patients were formed: patients with DR only and patients with DR and ON. For the development of only DR we can assume that the most important risk factor is the duration of DM, followed by the high levels of HbA1c, pre-pubertal age at onset, and arterial hypertension; and for the development of ON and DR simultaneously, risk factors are higher levels of HbA1c, arterial hypertension, DM duration and pre-pubertal age at onset.

Conclusions

In the current study, two major groups of patients have been formed, those who developed only DR and those who developed DR and ON. For the former, incidence increased as DM duration increased, and for the latter incidence appeared to be closely related to levels of HbA1c.

Introduction

Diabetes mellitus (DM) is defined as a group of metabolic diseases whose common feature is an elevated blood glucose level (hyperglycaemia). DM is a major worldwide health problem and in 2010 more than 200 million people were sufferers. The global population is predicted to increase by 62% between 1995 and 2025, and the prevalence of DM is expected to rise by over 120% (King et al., 1998, The Expert Committee on the Diagnosis and Classification of Diabetes Mellitus, 2000). Regarding type 1 DM (DM1), an increase in its incidence has also been observed in European children younger than 5 years, and it is predicted that between 2005 and 2020 cases in young people under 15 years will rise by 70% (Patterson et al., 2009).

DM is becoming the pandemic of the 21st century, now affecting more than 10% of those over 14 years in our Health Care Area (4 Abellana, Ascaso, Carrasco, Castell, & Tresserras, 2009). Chronic long-term morbidity will depend on two conditions, mainly macroangiopathy resulting in major vessels involvement and microangiopathy or small vessel involvement.

Microangiopathy affects the retinal vessels and leads the diabetic retinopathy (DR). Furthermore, the effect on the kidney leads to the overt nephropathy (ON). Currently, we know that an early form of kidney damage in DM1 patients is microalbuminuria (Stephenson, Fuller, Viberti, Sjolie, & The EURODIAB IDDM Complications Study Group, 1995), which is an early stage diabetic nephropathy. However, we do not know the retinal abnormalities that precede retinopathy, which would allow us to diagnose it early and try to prevent it from developing. We also know the most important risk factors that will induce DR, such as the time since onset of diabetes and elevated levels of glycosylated haemoglobin (HAb1c).

DR and ON presentation being forms of microangiopathy in both target organs, it would be logical to think that both appeared together, depending on the metabolic disorder caused by diabetes. However, retinal involvement exists in most cases of ON, but this not so when DR appears, since not all patients develop ON (El-Asrar et al., 2002, Rossing et al., 2002).

The objective of this study was to determine which risk factors lead to the development of DR, microalbuminuria and ON in DM1 patients. A prospective study of 20 years was carried out on a sample of patients without DR or microalbuminuria at baseline.

Section snippets

Setting

Hospital St Joan is the only public ophthalmology centre in Reus (Catalonia, Spain), and has a dependent population of 322,740. All DM1 patients are referred by general practitioners and endocrinologists. Since 1990, there has been an ongoing registration of all diabetic patients.

Design

A prospective, twenty-year study of a sample of 126 DM1 patients referred to our Health Care Area (HCA). The study was carried out on data from 1st January 1991 to 31st December 2010. Three previous sets of results

Demographic variables of the patients

A total of 110 patients (87.30%) completed the study at 31st December 2010. Applying the worst-case analysis, there would have been no differences between patients in a selected group even if the initial 126 patients (enrolled at 1st January, 1991) had completed the study. Table 1 shows the patients’ (47.3% were men and 52.7% were women) baseline characteristics, and diabetes duration was 29.99 (SD 7.51) years.

Incidence of diabetic retinopathy

At the 20-year follow up, there were 78 patients (70.91%) with DR and 35 patients

Discussion

In the largest epidemiological study ever carried out, that of Klein et al. in Wisconsin (Klein et al., 2010), the incidence of any DR was calculated at 83% (95% CI 80 to 86%) at 25 years follow up. In the present study, the 20-year incidence of any DR was 70.91%, with an incidence of sight-threatening diabetic retinopathy at 31.81%. The difference of five years between the lengths of the studies might be a reason for the lower percentage. The risk factors for DR were: DM1 duration, high

Authors’ Contribution

P.R-A. has contributed to the study design, researched data analysis, conducting the Discussion, and writing the manuscript.

M.B-B. has contributed to the ophthalmological data collection, the Discussion, the review and editing of the manuscript.

J.F-B. has contributed to the study design, statistical data analysis and interpretation of the study results.

N.P-G. has contributed to the study design, systemic disease diagnosis and laboratory analysis interpretation, researched data analysis and the

Acknowledgments

Medical School, University Rovira & Virgili of Tarragona, (Spain) for technical assistance.

Institut de Investigacio Sanitaria Pere Virgili (IISPV) for data analysis support and funding provision.

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    Institution: Hospital Universitari Sant Joan, Institut de Investigacio Sanitaria Pere Virgili (IISPV), Universitat Rovira & Virgili, (Reus) Spain.

    ☆☆

    Disclosure: Declaration of interest: The authors report no conflicts of interest. The authors alone are responsible for the content and writing of the paper.

    Conflict of interest: None of the authors has any potential conflicts of interest relevant to this article.

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