Serum lycopene levels in patients with diabetic retinopathy.

PURPOSE: Accumulating evidence indicates that oxidative stress may play an important role in the pathogenesis of type 2 diabetes and its complications. Lycopene, a very potent antioxidant of carotenoids, has received considerable scientific interest in recent years for its potential role in the prevention of oxidative stress-related chronic diseases. This study was undertaken to investigate whether the serum levels of lycopene are altered between type 2 diabetic patients with and without diabetic retinopathy. METHODS: A total of 71 patients with type 2 diabetes were analyzed and compared with 23 nondiabetic healthy controls. Serum lycopene concentrations were assayed using high-performance liquid chromatography. RESULTS: Lycopene level was found to be significantly lower in diabetic patients than in controls (p = 0.021). In the diabetic group, subjects with proliferative diabetic retinopathy had significantly lower lycopene levels than subjects without diabetic retinopathy or with nonproliferative diabetic retinopathy. In the analysis of correlations, hemoglobin A1c were negatively correlated with lycopene (r = -0.345, p = 0.007) after multivariate adjustment. A stepwise linear multiple regression model revealed that age and hemoglobin A1c were significant determinants of lycopene. CONCLUSIONS: Our findings show that measuring serum lycopene is a novel convenient method for evaluating oxidative damage. Diabetic patients, especially those with advanced diabetic retinopathy, had significantly lower serum lycopene levels; this suggests that lycopene may be helpful for the diagnosis, severity, and therapeutic evaluation of diabetic retinopathy.

Intensive therapy for diabetes through influence on innate immune system.

Steno-2 Study has previously shown that original intensive therapy reduced the risk of cardiovascular and microvascular events to about 50% of that of conventional treatment in type 2 diabetic patients. Further, in the subsequent follow-up study, intensive therapy was found to have sustained beneficial effects on cardiovascular events and death rate in this population. Another clinical trial, China Da Qing Diabetes Prevention Study, has recently reported that group-based lifestyle interventions over six years could prevent or delay the development of diabetes in patients with impaired glucose tolerance (IGT). The two famous intervention trials have demonstrated a consistent salutary effect of intensive therapy on the development and progression of diabetes and its complications. However, the exact mechanisms of the sustained beneficial effects remain to be elusive. There is a growing body of evidence to suggest that type 2 diabetes is associated with a general activation of the innate immune system, in which there is a chronic, cytokine-mediated state of low-grade inflammation. Some diabetic treatment agents with anti-inflammatory properties may lower both acute-phase reactants which are components of the innate immune system independent of their anti-hyperglycemic actions or lipid-lowering effects. The immunomodulatory effects of regular exercise, and in particular resistance training, may have positive effects on innate immunity and so may provide benefits for the profile of type 2 diabetes in addition to improving strength and functional abilities. Therefore, we speculate that the effects on the innate immune system through pharmacologic therapy or lifestyle modification such as exercise training are able to account - at least amongst others - for carry-over beneficial effects of multifactorial intervention on insulin resistance and type 2 diabetes. This hypothesis, if proved to be valid, might provide a new therapeutic option for the management of type 2 diabetes.