Background: Obesity and insulin resistance (IR) are risk factors for microvascular disease (MVD). Whether insulin-sensitive obese individuals are at higher risk for MVD is still debated. We aimed to investigate whether insulin-sensitive obesity is associated with retinal microvascular abnormalities.
Methods: This cross-sectional study recruited a total of 8,313 participants (3,604 males and 4,709 females) aged 21 years or older from 13 villages in rural area and 8 communities in urban area in Fujian province in China between 2011 to 2012. Participants were categorized by insulin-sensitive/-resistant and general/ abdominal obese status. IR was defined as homeostasis model assessment of IR >1.99 (75% percentile). Direct ophthalmoscopic examination was used to diagnose MVD, which was defined as the presence of retinal microvascular abnormalities.
Results: Among the older subjects (aged 65-79 years), those who were obese had a markedly higher risk for MVD, both in insulin-sensitive [odds ratio (OR): 2.259, 95% confidence interval (CI): 1.041-4.904, P=0.039] and insulin-resistant (OR: 2.356, 95% CI: 1.064-5.218, P=0.035) individuals. Additionally, insulinsensitive/-resistant abdominal obesity in middle-aged people showed an increased risk for prevalent MVD in women (OR: 2.061, 3.322; 95% CI: 1.004-4.233, 1.645-6.709; P values: 0.049, <0.001).
Conclusions: In this study, obesity was closely related to an elevated higher risk of MVD, regardless of IR, especially in older people and abdominally obese middle-aged women. Obesity may be similar to diabetes mellitus, with chronic complications that not only cause cardiovascular diseases but also MVD. Direct ophthalmoscopy may be a noninvasive and meaningful method of early screening for obesity-related MVD. Insulin-sensitive obesity, like impaired glucose tolerance, is a pre-existing state of insulin resistant obesity.
Keywords: Insulin-sensitive obesity; obesity; retinal microvascular abnormalities.