Preliminary analysis of the macular retinal thickness in early stage of type 2 diabetes mellitus and impaired glucose tolerance patients

Objective To analyze the alteration of the macula retinal thickness in early stage of type 2 diabetes mellitus and impaired glucose tolerance patients. Methods An observational crosssectional study. After excluding a series of systematic and ocular abnormalities, 62 cases of epidemiology investigative subjects of community residents aged from 45 to 70 were divided into type2 diabetic mellitus (T2DM), impaired glucose tolerance (IGT), and normal control (CTR) group, followed by the WHO DM diagnostic criteria. All the subjects’macula were scanned by spectral-domain ocular coherence tomography (SD-OCT) with the mode of 6mm ETDRS. Data of macular retinal thickness were analyzed using SAS statistic software among the groups. Results With comparison of CTR, macular retinal thickness in T2DM group has the tendency of attenuation; IGT group show thickening. Inner nuclear layer (INL), inner retinal layer (IRL) and outer retinal layer (ORL) inT2DM group were significantly attenuated than those of CTR group. With comparison of T2DM, IGT group has significant thicker in IPL, RPEL, INL and IRL. Conclusions INL might be attenuated and atrophied during early stage of T2DM patients when no diabetic retinopathy occur; IGT might increase the thickness of the inner retina and cause retinal edema. Structural alteration might be occurred during diabetic early stage and IGT, which might differ from and prior to the microangiopathy as well, suggesting that early stage of T2DM and IGT might lead to retinal neurodegeneration. Key words: Diabetic mellitus; Impaired glucose tolerance; Inner retina; Inner plexiform layer; Inner nuclear layer; Neurodegeneration