Type 2 diabetes (T2D) is a true silent pandemic: globally, in the last two decades alone, the number of people affected has risen from 150 million to more than 350 million. T2D currently represents one of the main causes of blindness in adults, due to its main ocular complications: diabetic retinopathy and diabetic macular oedema.
Prevention and early diagnosis could be winning strategies, but unfortunately there is still limited data available on the paediatric target group of children and young people with T2D and their visual problems, in particular diabetic retinopathy.
In 2023, the systematic review was published Global Prevalence of Diabetic Retinopathy in Paediatric Type 2 Diabetes: A Systematic Review and Meta-analysis with the aim of determining the overall prevalence of diabetic retinopathy in paediatric patients with T2D. Influential factors such as disease duration, gender, race, age, glycated haemoglobin (HbA1c) levels, presence of obesity and hypertension were also taken into account.
Risk factors
L'obesityincreasingly widespread and early, is a primary causal factor in determining the overall growth of T2D in children and adolescents in whom diabetes manifests itself as a more aggressive pathology compared to adults, with comorbidities and early complications including hypertension, nephropathy, polycystic ovary syndrome and dyslipidaemia.
In paediatric patients, diabetic retinopathy represents the main complication that can cause blindness in adulthood, through a sequence of concatenated events in which hyperglycaemia increases vascular permeability and can lead to capillary occlusion, resulting in the onset of non-proliferative diabetic retinopathy. This initial phase may be followed by a phase characterised by the formation of blood neovases, typical of proliferative diabetic retinopathy. Macular oedema may also develop with accumulation of fluid in the macular area and subsequent impact on central vision.
Children generally develop T2D very early and, as a result, find themselves living with diabetes for several decades and the extended duration systemic pathology is an increased risk factor for developing diabetic retinopathy later in life and eventually blindness if the retinopathy is not diagnosed and treated appropriately. Unfortunately, while current guidelines recommend screening for early diagnosis of diabetic retinopathy in young people with T2D, the global figure for paediatric diabetic retinopathy has not yet been fully quantified.
Epidemiological trends
The systematic review just mentioned collected data from 27 observational studies available in the literature, involving a total of 5,924 paediatric patients with T2D. The overall prevalence of diabetic retinopathy was found to be 6.99% and this percentage increases significantly after the first 5 years after diagnosis.
According to current data, approximately 1 in every 14 children or adolescents with T2D develops diabetic retinopathy within a few years of diagnosis. Most of the young patients observed fortunately present with a mild or minimal form of non-proliferative diabetic retinopathy, and only a small minority develop a severe form of proliferative diabetic retinopathy or macular oedema, which can lead to severe visual impairment and potentially irreversible vision loss.
If we compare these results with the data concerning adults with T2D, we see that between 21% and 39% of patients already have retinopathy when they are first diagnosed with diabetes, and that this percentage is set to increase thereafter. Early diagnosis therefore proves to be a decisive factor in combating the complications of diabetes.
Hyperglycaemia can lead to structural and functional retinal abnormalities in patients with T2D as early as 2 years after diagnosis. In addition, adolescents with T2D have a lower retinal thickness and greater retinal venular dilatation compared to non-diabetic patients.
These data underline the importance of screening targeted for early detection of diabetic retinopathy in paediatric patients with T2D to prevent blindness and low vision.
The benefits of early identification of diabetic retinopathy include an increased focus on improved glycaemic control to minimise microvascular complications and close monitoring of blood pressure, which have already been shown to be crucial parameters in both adults and paediatric patients with type 1 diabetes.
Screening methods
The method used for screening has important implications in determining the prevalence rate of diabetic retinopathy and also explains some heterogeneity between different studies. By far, 7-field fundus stereoscopic photography is the gold standard and is preferred to fundoscopy, which is complex to perform in paediatric patients. Compared with stereoscopic fundus 7-field photography, indirect fundoscopy has a sensitivity of 76% and a specificity of 95%.
Fundus photography requires specific equipment and highly skilled personnel to acquire the images and perform the analysis. These technologies may not be accessible in low- and middle-income countries where T2D rates are rapidly increasing and this inequality in access to healthcare has an impact on adherence and generalisability of screening guidelines.
New technologies, and in particular applications of artificial intelligence (AI), such as some low-cost equipment, automated grading of retinal images and virtual consultation with specialists could offer the opportunity for fairer access. Automated detection systems based on artificial intelligence have been shown to have a sensitivity of 87% and a specificity of 79.3% in diagnosing diabetic retinopathy in young patients. The use of these instruments has not yet been approved in children, but could represent a very promising solution as it does not require direct supervision by ophthalmologists and can, therefore, be used in settings where these specialists are lacking.
On the subject of diabetic retinopathy, we also suggest:
- Diabetic retinopathy: towards 2030 - Oculista Italiano
- Diabetic retinopathy in pregnancy - Oculista Italiano
- Type 2 diabetes and retinopathy: different phenotypes predict progression - Oculista Italiano
- Cioana M, Deng J, Nadarajah A, et al. Global Prevalence of Diabetic Retinopathy in Paediatric Type 2 Diabetes: A Systematic Review and Meta-analysis. JAMA Netw Open. 2023 Mar 1;6(3):e231887. doi: 10.1001/jamanetworkopen.2023.1887
- Samaan MC, Cioana M, Banfield L, et al. The prevalence of comorbidities in paediatric type 2 diabetes mellitus: a systematic review. International Prospective Register of Systematic Reviews (PROSPERO) identifier: CRD42018091127. March 19, 2018. Accessed January 30, 2023. http://www.crd.york.ac.uk/PROSPERO/display_record.php?ID=CRD42018091127
- Cioana M, Deng J, Nadarajah A, et al. The prevalence of obesity among children with type 2 diabetes: a systematic review and meta-analysis. JAMA Netw Open. 2022;5(12):e2247186. doi: 10.1001/jamanetworkopen.2022.47186.
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