On 2017 Jan 18, Martin Hofmeister commented:

Physical activity is an underestimated modifiable factor

I thank Wat et al. for their very interesting review article "Associations between diabetic retinopathy and systemic risk factors" in the December 2016 issue of the Hong Kong Medical Journal. I agree with the authors but there is one lifestyle aspect worth mentioning. Recent studies suggest that regular physical activity can be a protective factor for the development of diabetic retinopathy (DR) and microvascular diabetes-related complications [1-6]. Physical activity and exercise is characterized by a simultaneous antihyperglycemic (reduction in haemoglobin A1c of -0.6%), antihyperlipidemic, antihypertensive, antioxidative, anti-inflammatory, and cardioprotective effects.

An example of neurobiological adaptations to exercise is the increased expression of neuroprotective factors such as brain-derived neurotrophic factor (BDNF) in the brain, blood, and muscles. Decreased plasma levels of BDNF were detected as an independent risk factor for DR and vision-threatening DR in Chinese type 2 diabetic patients [7-8]. The downregulation of BDNF probably has an important role in the complex and multifactorial pathogenesis of DR [9].

In a first study, Loprinzi also observed a positive association between sedentary behavior and DR [10]. The American Diabetes Association has recently updated its evidence-based recommendations on physical activity and exercise for diabetic patients. The main innovation is that diabetics should minimize the total amount of daily sedentary time. Prolonged sitting time should be interrupted every 30 min with brief (≤5 min) bouts of standing or light activity to improve the glycemic control [11].

In the case of severe nonproliferative and unstable proliferative retinopathy, it is recommended that vigorous-intensity activities be avoided [11].

REFERENCES

1) Dirani M, Crowston JG, van Wijngaarden P. Physical inactivity as a risk factor for diabetic retinopathy? A review. Clin Exp Ophthalmol 2014;42(6):574-81. Dirani M, 2014

2) Loprinzi PD, Brodowicz GR, Sengupta S, Solomon SD, Ramulu PY. Accelerometer-assessed physical activity and diabetic retinopathy in the United States. JAMA Ophthalmol 2014;132(8):1017-9. Loprinzi PD, 2014

3) Gutiérrez Manzanedo JV, Carral San Laureano F, García Domínguez G, Ayala Ortega C, Jiménez Carmona S, Aguilar Diosdado M. High prevalence of inactivity among young patients with type 1 diabetes in south Spain. Nutr Hosp. 2014;29(4):922-8. Gutiérrez Manzanedo JV, 2014

4) Loprinzi PD. Concurrent healthy behavior adoption and diabetic retinopathy in the United States. Prev Med Rep. 2015;2:591-4. Loprinzi PD, 2015

5) Li Y, Wu QH, Jiao ML, Fan XH, Hu Q, Hao YH, Liu RH, Zhang W, Cui Y, Han LY. Gene-environment interaction between adiponectin gene polymorphisms and environmental factors on the risk of diabetic retinopathy. J Diabetes Investig. 2015;6(1):56-66. Li Y, 2015

6) Praidou A, Harris M, Niakas D, Labiris G. Physical activity and its correlation to diabetic retinopathy. J Diabetes Complications. 2016 Jun 29. pii: S1056-8727(16)30256-2. doi: 10.1016/j.jdiacomp.2016.06.027. [Epub ahead of print]. Praidou A, 2017

7) Liu SY, Du XF, Ma X, Guo JL, Lu JM, Ma LS. Low plasma levels of brain derived neurotrophic factor are potential risk factors for diabetic retinopathy in Chinese type 2 diabetic patients. Mol Cell Endocrinol 2016;420:152-8. Liu SY, 2016

8) Guo M, Liu H, Li SS, Jiang FL, Xu JM, Tang YY. LOW SERUM BRAIN-DERIVED NEUROTROPHIC FACTOR BUT NOT BRAIN-DERIVED NEUROTROPHIC FACTOR GENE VAL66MET POLYMORPHISM IS ASSOCIATED WITH DIABETIC RETINOPATHY IN CHINESE TYPE 2 DIABETIC PATIENTS. Retina. 2016 Jun 27. [Epub ahead of print]. Guo M, 2017

9) Behl T, Kotwani A. Downregulated Brain-Derived Neurotrophic Factor-Induced Oxidative Stress in the Pathophysiology of Diabetic Retinopathy. Can J Diabetes. 2016 Nov 29. pii: S1499-2671(16)30079-X. doi: 10.1016/j.jcjd.2016.08.228. [Epub ahead of print]. Behl T, 2017

10) Loprinzi PD. Association of Accelerometer-Assessed Sedentary Behavior With Diabetic Retinopathy in the United States. JAMA Ophthalmol 2016;134(10):1197-8. Loprinzi PD, 2016

11) Colberg SR, Sigal RJ, Yardley JE, Riddell MC, Dunstan DW, Dempsey PC, Horton ES, Castorino K, Tate DF. Physical activity/exercise and diabetes: a position statement of the American Diabetes Association. Diabetes Care 2016; 39(11): 2065-79. Colberg SR, 2016

On 2017 Jan 18, Martin Hofmeister commented:

Physical activity is an underestimated modifiable factor

I thank Wat et al. for their very interesting review article "Associations between diabetic retinopathy and systemic risk factors" in the December 2016 issue of the Hong Kong Medical Journal. I agree with the authors but there is one lifestyle aspect worth mentioning. Recent studies suggest that regular physical activity can be a protective factor for the development of diabetic retinopathy (DR) and microvascular diabetes-related complications [1-6]. Physical activity and exercise is characterized by a simultaneous antihyperglycemic (reduction in haemoglobin A1c of -0.6%), antihyperlipidemic, antihypertensive, antioxidative, anti-inflammatory, and cardioprotective effects.

An example of neurobiological adaptations to exercise is the increased expression of neuroprotective factors such as brain-derived neurotrophic factor (BDNF) in the brain, blood, and muscles. Decreased plasma levels of BDNF were detected as an independent risk factor for DR and vision-threatening DR in Chinese type 2 diabetic patients [7-8]. The downregulation of BDNF probably has an important role in the complex and multifactorial pathogenesis of DR [9].

In a first study, Loprinzi also observed a positive association between sedentary behavior and DR [10]. The American Diabetes Association has recently updated its evidence-based recommendations on physical activity and exercise for diabetic patients. The main innovation is that diabetics should minimize the total amount of daily sedentary time. Prolonged sitting time should be interrupted every 30 min with brief (≤5 min) bouts of standing or light activity to improve the glycemic control [11].

In the case of severe nonproliferative and unstable proliferative retinopathy, it is recommended that vigorous-intensity activities be avoided [11].

REFERENCES

1) Dirani M, Crowston JG, van Wijngaarden P. Physical inactivity as a risk factor for diabetic retinopathy? A review. Clin Exp Ophthalmol 2014;42(6):574-81. Dirani M, 2014

2) Loprinzi PD, Brodowicz GR, Sengupta S, Solomon SD, Ramulu PY. Accelerometer-assessed physical activity and diabetic retinopathy in the United States. JAMA Ophthalmol 2014;132(8):1017-9. Loprinzi PD, 2014

3) Gutiérrez Manzanedo JV, Carral San Laureano F, García Domínguez G, Ayala Ortega C, Jiménez Carmona S, Aguilar Diosdado M. High prevalence of inactivity among young patients with type 1 diabetes in south Spain. Nutr Hosp. 2014;29(4):922-8. Gutiérrez Manzanedo JV, 2014

4) Loprinzi PD. Concurrent healthy behavior adoption and diabetic retinopathy in the United States. Prev Med Rep. 2015;2:591-4. Loprinzi PD, 2015

5) Li Y, Wu QH, Jiao ML, Fan XH, Hu Q, Hao YH, Liu RH, Zhang W, Cui Y, Han LY. Gene-environment interaction between adiponectin gene polymorphisms and environmental factors on the risk of diabetic retinopathy. J Diabetes Investig. 2015;6(1):56-66. Li Y, 2015

6) Praidou A, Harris M, Niakas D, Labiris G. Physical activity and its correlation to diabetic retinopathy. J Diabetes Complications. 2016 Jun 29. pii: S1056-8727(16)30256-2. doi: 10.1016/j.jdiacomp.2016.06.027. [Epub ahead of print]. Praidou A, 2017

7) Liu SY, Du XF, Ma X, Guo JL, Lu JM, Ma LS. Low plasma levels of brain derived neurotrophic factor are potential risk factors for diabetic retinopathy in Chinese type 2 diabetic patients. Mol Cell Endocrinol 2016;420:152-8. Liu SY, 2016

8) Guo M, Liu H, Li SS, Jiang FL, Xu JM, Tang YY. LOW SERUM BRAIN-DERIVED NEUROTROPHIC FACTOR BUT NOT BRAIN-DERIVED NEUROTROPHIC FACTOR GENE VAL66MET POLYMORPHISM IS ASSOCIATED WITH DIABETIC RETINOPATHY IN CHINESE TYPE 2 DIABETIC PATIENTS. Retina. 2016 Jun 27. [Epub ahead of print]. Guo M, 2017

9) Behl T, Kotwani A. Downregulated Brain-Derived Neurotrophic Factor-Induced Oxidative Stress in the Pathophysiology of Diabetic Retinopathy. Can J Diabetes. 2016 Nov 29. pii: S1499-2671(16)30079-X. doi: 10.1016/j.jcjd.2016.08.228. [Epub ahead of print]. Behl T, 2017

10) Loprinzi PD. Association of Accelerometer-Assessed Sedentary Behavior With Diabetic Retinopathy in the United States. JAMA Ophthalmol 2016;134(10):1197-8. Loprinzi PD, 2016

11) Colberg SR, Sigal RJ, Yardley JE, Riddell MC, Dunstan DW, Dempsey PC, Horton ES, Castorino K, Tate DF. Physical activity/exercise and diabetes: a position statement of the American Diabetes Association. Diabetes Care 2016; 39(11): 2065-79. Colberg SR, 2016