Editing Diabetic retinopathy (section)

===Risk factors===
The major risk factors for developing diabetic retinopathy are duration of diabetes, poor blood sugar control, and to a lesser extent high blood pressure.{{sfn|Vujosevic|Aldington|Silva|Hernández|2020|loc="Risk factors for diabetic retinopathy"}} Five years after diabetes diagnosis, around 25% of those with type 1 diabetes have some degree of diabetic retinopathy, while 2% have proliferative diabetic retinopathy. By 15 years after diagnosis, that increases to 80% with some retinopathy, and 25% with proliferative disease.{{sfn|Brownlee|Aiello|Sun|Cooper|2020|loc="Initial ophthalmic evaluation"}} Children are an exception—regardless of duration of diabetes, children rarely experience sight-threatening retinopathy; however, [[puberty]] can accelerate retinopathy progression.{{sfn|Brownlee|Aiello|Sun|Cooper|2020|loc="Initial ophthalmic evaluation"}} Pregnancy can also accelerate the progression of diabetic retinopathy (although women with [[gestational diabetes]] are not at risk).{{sfn|Brownlee|Aiello|Sun|Cooper|2020|loc="Initial ophthalmic evaluation"}}

Both chronically high blood sugar (measured by a high [[HbA1c]]) and highly variable blood sugar are associated with developing diabetic retinopathy.{{sfn|Lin|Hsih|Lin|Wen|2021|loc="Risk factors, preventive factors, and biomarkers"}} Several more minor risk factors also exacerbate diabetic retinopathy, namely [[nephropathy|kidney disease]], [[Dyslipidemia|abnormal blood lipids]], high [[body mass index]], and [[smoking]].{{sfn|Lin|Hsih|Lin|Wen|2021|loc="Risk factors, preventive factors, and biomarkers"}}

Genetic predisposition to diabetic retinopathy in type 2 diabetes consists of many genetic variants across the genome that are collectively associated with diabetic retinopathy ([[Polygenic score|polygenic risk]]) and overlaps with genetic risk for [[glucose]], [[Low-density lipoprotein|low-density lipoprotein cholesterol]], and [[systolic blood pressure]].<ref name=":4">{{cite journal | vauthors = Forrest IS, Chaudhary K, Paranjpe I, Vy HM, Marquez-Luna C, Rocheleau G, Saha A, Chan L, Van Vleck T, Loos RJ, Cho J, Pasquale LR, Nadkarni GN, Do R | title = Genome-wide polygenic risk score for retinopathy of type 2 diabetes | journal = Human Molecular Genetics | volume = 30 | issue = 10 | pages = 952–960 | date = May 2021 | pmid = 33704450 | pmc = 8165647 | doi = 10.1093/hmg/ddab067 }}</ref> Several variations in the ''[[VEGFC]]'' gene have also been associated with an increased risk of developing macular edema.{{sfn|Tan|Cheung|Simó|Cheung|2017|loc="Risk factors"}}

People with [[Down syndrome]], who have extra [[chromosome 21]] material, almost never acquire diabetic retinopathy. This protection appears to be due to the elevated levels of [[endostatin]],<ref>{{cite journal | vauthors = Ryeom S, Folkman J | title = Role of endogenous angiogenesis inhibitors in Down syndrome | journal = The Journal of Craniofacial Surgery | volume = 20 | issue = Suppl 1 | pages = 595–596 | date = March 2009 | pmid = 19795527 | doi = 10.1097/SCS.0b013e3181927f47 | s2cid = 21576950 }}</ref> an anti-angiogenic protein, derived from [[type XVIII collagen|collagen XVIII]]. The collagen XVIII gene is located on chromosome 21.

Incidence of [[Retinitis pigmentosa|Retinitis Pigmentosa]] is observed to result in fewer and less severe microvascular lesions in both humans and mouse models.<ref>{{cite journal | vauthors = de Gooyer TE, Stevenson KA, Humphries P, Simpson DA, Gardiner TA, Stitt AW | title = Retinopathy is reduced during experimental diabetes in a mouse model of outer retinal degeneration | journal = Investigative Ophthalmology & Visual Science | volume = 47 | issue = 12 | pages = 5561–5568 | date = December 2006 | pmid = 17122149 | doi = 10.1167/iovs.06-0647 | doi-access = free }}</ref> Retinitis Pigmentosa results in loss of rod receptors in the mid peripheral field, reducing the oxygen consumption that is linked with release of [[Vascular endothelial growth factor|VEGF]] and growth of unwanted blood vessels in the retina.

Obstructive [[sleep apnea]] (OSA) has been associated with a higher incidence of diabetic eye disease due to blood desaturation caused by intermittent upper airway obstructions. Treatment for OSA can help reduce the risk of diabetic complications.<ref>{{Cite news|url=https://www.news-medical.net/health/Diabetes-and-Vision.aspx|title=Diabetes and Vision|date=2018-04-04|work=News-Medical.net|access-date=2018-04-10|language=en}}</ref>