In recent years, some researches show that getting younger over the diabetes mellitus (DM) was an obrious trend. But studies of early diabetic retinopathy in young people with diabetes were few. Both patients and doctors did not put enough importance on it.

This study was to evaluate the earlier dynamic changes of retina morphology and function caused by type 2 DM in young population.

A cohort study was designed. One hundred and thirty-six young patients who were initially diagnosed as type 2 DM in Cangzhou Central Hospital were included from January to March in 2010 and 91 healthy individuals with the matched age were enrolled at the same period. Glycated hemoglobin (HbAlc) level in blood was assayed yearly, and ophthalmoscope, optical coherence tomography (OCT) and visual contrast sensitivity (CS) examinations were performed to evaluate the dynamic changes of retinal nerve fiber layer (RNFL) thickness around optical disc, retinal function and retinal microvessels of DM patients. In addition, the correlation between RNFL thickness or CS and average HbAlc level in DM patients was assessed. This study followed Declaration of Helsinki, and written informed consent was obtained from each subject.

The levels of HbAlc in DM patients were (7. 5±1. 6)%, (7. 2±1. 6)%, (7. 4±1. 6)%, (7. 6±1. 6)% and (7. 7±1. 6)% in 2010, 2011, 2012, 2013 and 2014, respectively, and HbAlc≥7. 0% was observed in 74 patients (54. 4%). The RNFL thicknesses of full optic disk and superior 1/4 quadrant of the optic disk were significantly declined in 2012, 2013 and 2014 in the DM group compared with the normal control group (full disk: t=2. 216, 5. 003, 7. 303; all at P<0. 05. superior 1/4 quadrant: t=2. 382, 5. 657, 7. 194; all at P<0. 05), but no significant differences were found between them in 2010 and 2011 (all at P>0. 05). In the DM group, RNFL thicknesses of full optic disk were (99. 94±10. 01)μm and (96. 32±10. 32)μm in 2013 and 2014, which were significantly lower than (104. 55±9. 23)μm in 2010 (t=7. 819, 13. 959, both at P<0. 05); the RNFL thicknesses of superior 1/4 quadrant around disk were (118. 64±13. 98)μm and (115. 06±14. 35)μm in 2013 and 2014, which were significantly lower than (127. 48±13. 67)μm in 2010 (t=10. 504, 14. 758, both at P<0. 05), However, the RNFL thicknesses were not significantly changed among the different time points in the normal control group (all at P>0. 05). In addition, the CS values of 3. 0, 6. 0, 12. 0, 18. 0 c/d in 2013 and 2014 in the DM group were lower than those in the normal control group (all at P<0. 05), and the CS values in 2013 and 2014 were reduced in comparison with 2010 in the DM group (all at P<0. 05). Positive correlations were found between the differences of RNFL thickness or CS and the average HbAlc level in the DM group (r=0. 640, F=8. 991, P=0. 000; r=0. 541, F=7. 572, P=0. 000). Retinal microaneurysms were seen in two type 2 DM patients by ophthalmoscope at the end of follow-up.

The young people with type 2 DM have poor blood glucose control. The RNFLs are thinning and visual functions are declining in young type 2 DM patients with the lapse of disease course, and these retinal damages are associated with poor control of blood glucose.

Diabetes mellitus/complication; Retinopathy; Nerve fiber layer, retina; Optical coherence tomography; Contrast sensitivity; Glycated hemoglobin; Young adult