ABSTRACT
The relationship between oxidative stress and the first-phase of pancreatic β cell insulin secretion in subjects with different statuses of glucose tolerance was explored. Fasting adiponectin, 8-hydroxydeoxyguanosin ( 8-OHdG), malondialdehyde ( MDA ), superoxide dismutase ( SOD ), insulin area under the curve ( AUC ) from 0 to 10 min, and AIR3-5 were measured. The levels of oxidative stress-related markers were elevated, the activities of superoxide dismutase,adiponectin, and first-phase of insulin secretion were reduced with the disease progression. MDA and 8-OHdG were negatively correlated with adiponectin, homeostasis model assessment β cell function index ( HOMA-β ),AUC ,and AIR3-5. SOD was positively correlated with adiponectin, HOMA-β, AUC, AIR3-5. The plasma 8-OHdG and SOD were independently associated with AIR3-5. Oxidative stress exerts a significant effect on the first phase of pancreatic β cell insulin secretion, which may contribute to the pathogenesis of type 2 diabetes.
ABSTRACT
Objective To investigate the relationship between angiotensin Ⅱ and pancreatic islet β cell secretion function under different glucose tolerance statuses. Method Forty-two patients with newly diagnosed type 2diabetes mellitus ( DM group), 38 subjects with impaired fasting glucose/impaired glucose tolerance ( IFG/IGTgroup) ,and 40 normal control subjects (NGT group) underwent intravenous glucose tolerance test. Fasting plasma angiotensin Ⅱ ( Ang Ⅱ ) and adiponectin were assayed by ELISA. Acute insulin response from 3 to 10 min( AIR3-10 ),the area under the curve( AUCⅠ ) and the peak concentration of the first-phase ( 0-10 min) insulin secretion, the area under the curve of the second-phase( 10-120 min) insulin secretion( AUCⅡ), homeostasis model assessment for β cell function index(HOMA-β) and homeostasis model assessment for insulin resistance index(HOMA-IR) were calculated to explore the relationship with Ang Ⅱ. Result ( 1 ) The levels of Ang Ⅱ in DM group and IFG/IGT group were significantly higher than that in NGT group( P＜0.05 ). The AIR3-10, AUCⅠ and peak concentration, AUCⅡ ,adiponectin in DM group and IFG/IGT group were significantly lower than those in the NGT group ( P＜0. 05), and these results were more significantly reduced in DM group compared with those in IFG/IGT group. (2) Ang Ⅱ was negatively correlated with AIR3-10, AUCⅠ and the peak concentration, AUCⅡ, adiponectin, HOMA-β ( P＜0. 01 ), and positively correlated with fasting blood glucose,2 h blood glucose after glucose loading, fasting insulin, HOMA-IR (P＜0. 05 ). (3)Multiple stepwise regression analysis showed that Ang Ⅱ was independently associated with AUCⅠ and AUCⅡ.Conclusion Ang Ⅱ was an independent factor that affected the insulin secretion function of pancreatic islet βcells. Ruling out the effect of blood pressure, body position, drugs, and other factors, high levels of Ang Ⅱ could predict the dysfunction of pancreatic islet β cell as well as insulin resistance in patients with type 2 diabetes.
ABSTRACT
Objective To investigate the relationship between adiponectin and the first-phase of pancreatic P-cell insulin secretion in subjects with different statuses of glucose tolerance. Methods Thirty-seven patients with newly diagnosed type 2 diabetes mellitus (DM) , 30 patients with abnormal glucose tolerance (IGR) , and 40 normal control subjects (NGT) underwent intravenous glucose tolerance test (IVGTT). Fasting adiponectin and proinsulin (PI) was assayed by EL1SA. Fasting free fatty acid ( FFA) was measured by colorimetry. Insulin area under the curve ( AUC ) , incremental AUC (iAUC) from 0 min to 10 min, AIR3-5, homeostasis model assessment for insnlin resistance (HOMA-IR) , and for β cell function ( HOMA-p) were calculated. The relationship between adiponectin and AUC, iAUC, AIR3-5, proinsulin, FFA, and HOMA-IR was explored. Results (1) The levels of AUC, iAUC, AIR3-5, and adiponectin in DM group and IGR group were significantly lower than those in NGT group (P<0.05), reduced in DM group than those in IGR group(P<0.05). (2) The levels of PI in DM group and IGR group were significantly higher than that in NGT (P<0.05). (3) Adiponectin was positively correlated with HOMA-p,AUC,iAUC,AIR3-5, and HDL-C,while negatively correlated with proinsulin, HOMA-IR, and LDL-C. (4) Proinsulin was positively correlated with HOMA-IR. (5 ) Multiple regression stepwise analysis showed that adiponectin was independently associated with AUC. Conclusions Adiponectin was an independent factor affecting the first phase of pancreatic p-cell insulin secretion. Low adiponectin level could predict the dysfunction of the first phase pancreatic p-cell secretion as well as insulin resistance in patients with type 2 diabetes.