Background Higher incidence of SDB has been reported from West in patients having sight threatening retinopathy with limited information from South Asia.
Methods It was a prospective, observational study carried out on 80 patients of type 2 DM presented to Vitreo-retinal clinic. Patients with coronary artery disease, acute and chronic Heart Failure, concurrent hypothyroidism, known Obstructive sleep apnea (OSA) with DM and of any known respiratory disorder were excluded.
On the basis of fundus and fluorescein angiography they were divided into two Groups, Group I without retinopathy (n=30) and Group II with retinopathy (n=50). Latter had 30 and 20 patients of Non Proliferative Diabetic retinopathy (NPDR) and Proliferative Diabetic retinopathy (PDR) respectively. All patients underwent whole night attended polysomnography in the hospital.
Results The patients having diabetic retinopathy had higher age, BMI, waist circumference, Serum creatinine, HbA1c and Apnea Hypoapnea index (AHI) (p<0.05). PDR sub-group had a higher waist and neck circumference however NPDR patients had a higher HbA1c (p<0.05). OSA was observed in 66% and 40% of patients with & without diabetic retinopathy (12/30 vs. 33/50) respectively. On subgroup analysis, 90% of patients having PDR had OSA as compared to 50% in NPDR group. Severity of OSA was proportional to the presence of retinopathy (AHI=24.35±27.72 vs. 13.09±20.3 in Gp II & Gp.I respectively). It was nearly twice as severe in PDR Group than NPDR Group ((34.91±30.61 vs 17.3±23.94) with significantly higher desaturation (5.37±5.09% vs. 11.53±6.82%). On multivariate regression analysis only HbA1c levels correlated with presence of SDB in Diabetics.
Conclusion In a selective hospital based population of type 2 DM, prevalence and severity of SDB correlated with severity of retinopathy. A larger longitudinal study is need of the hour to predict factors responsible for OSA and find correlation between SDB with diabetic retinopathy.
Key words sleep disordered breathing, type 2 Diabetes Mellitus, NPDR, PDR, Apnea Hypoapnea Index.