A biomarker study of Chinese type 2 diabetic subjects : relationships between antioxidants, oxidative stress, hyperglycaemia and APOE polymorphism, and the effect of ginseng supplementation on antioxidants and oxidative stress

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A biomarker study of Chinese type 2 diabetic subjects : relationships between antioxidants, oxidative stress, hyperglycaemia and APOE polymorphism, and the effect of ginseng supplementation on antioxidants and oxidative stress

 

Author: Ma, Shuk-woon
Title: A biomarker study of Chinese type 2 diabetic subjects : relationships between antioxidants, oxidative stress, hyperglycaemia and APOE polymorphism, and the effect of ginseng supplementation on antioxidants and oxidative stress
Degree: Ph.D.
Year: 2008
Subject: Hong Kong Polytechnic University -- Dissertations.
Non-insulin-dependent diabetes.
Biochemical markers.
Antioxidants.
Oxidative stress.
Department: Dept. of Health Technology and Informatics
Pages: xxii, 234 leaves : ill. (some col.) ; 30 cm.
Language: English
InnoPac Record: http://library.polyu.edu.hk/record=b2239119
URI: http://theses.lib.polyu.edu.hk/handle/200/5167
Abstract: Type 2 diabetes is a serious health problem causing long-term complications and huge socioeconomic burden. Risk factors for complications include smoking, hypertension, hyperlipidaemia, poor glycaemic control, increased oxidative stress and genetic factors, but adequate risk assessment is still not possible at the individual level, and underlying causes of complications are not totally resolved. In diabetes treatment there is worldwide interest in incorporating traditional herbs, such as ginseng, into modern approaches to patient management, but this needs scientific validation. This study had three areas of focus in regard to type 2 diabetes: 1. Antioxidants, oxidative stress and acute elevation of plasma glucose; here, controlled studies of consenting normal (n=10) and type 2 diabetic (n=20) subjects were performed during a standard 75 g OGTT; 2. Association of a specific genetic factor, APOE (with c2 allele of particular interest), with type 2 diabetes and renal complications; here, APOE genotyping of 405 consenting Chinese type 2 diabetic patients in Hong Kong was performed, along with a 'baseline' (entry) biomarker profile; 321 subjects were followed for up to 4 years for evidence of renal complications; 3. Potential benefit of Asian ginseng (Panax ginseng) in type 2 diabetes; here, a placebo-controlled supplementation study of cross-over design with 20 consenting Chinese type 2 diabetic subjects was performed, and in vitro antioxidant capacity of the supplement and commercially available ginseng products (n=31) was performed. Results showed 1) no significant acute change in antioxidant or oxidative stress biomarkers in healthy or type 2 diabetic subjects during OGTT, although chronic oxidative stress was present in the diabetes patients; ascorbate levels of type 2 diabetic patients were relatively good; 2) no relationship between the e2 allele and type 2 diabetes or renal impairment; no relationship between the &2 allele and glycaemic control, blood pressure; an exploration of APOE polymorphism with biomarkers of oxidative stress and antioxidants showed e3/3 carriers had higher plasma ascorbate; 3) lower insulin resistance with ginseng supplementation, but no significant change in antioxidant or oxidative stress biomarkers or plasma lipids; antioxidant capacity of all ginseng products tested was low. Results challenge the accepted view that acute elevation of glucose induces a marked and direct increase in oxidative stress. This might be because of limitations in biomarkers and time-frame used in the study, or because of a protective effect of ascorbate. It may also be that increased oxidative stress in diabetes, which is not disputed, is due to chronic or variable hyperglycaemia. Results do not support previous suggestions that APOE polymorphism is related to development of type 2 diabetes or renal complications. While identifying genetic component(s) responsible for the development of diabetes or complications would be useful to identify high risk individuals, APOE genotyping cannot be recommended as useful in this regard. Ginseng, through insulin sensitising properties, could help treat type 2 diabetes, and even salvage insulin-resistant subjects so as to prevent their progression to overt diabetes, but effects are unlikely to be related to antioxidant effects.

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