| ObjectiveTo investigate the relationship between the alteration of serum melatonin (MT)level and its secretion rhythm and oxidative stress in patients with type2diabetes.Methods32patients with type2diabetic mellitus (DM group) and16cases of health volunteers (NC group)were selected as study subjects. DM group was further divided into macrovascular subgroup(MV) and nonmacrovascular subgroup(NMV).All of the subjects, respectively, were taken cubital vein at02:00(t2) and08:00(t8), then serum was separated immediately and packing stored in-80℃refrigerator. At night,the patients were awakened, then put on opaque goggles, blood drawing was completed within five minutes; At08:00, the patients must be fasting and clearheaded more than half an hour. The concentration of serum MT was detected by ELISA, the serum superoxide dismutase (SOD) was detected by xanthine oxidase method,and serum nitric oxide (NO) was by enzymatic nitrate reductase. The ratio of every above index at t2to t8was used to indicate its circadian rhythms change.Fasting plasma glucose (FPG), glycosylated hemoglobin (HbAlc), total cholesterol (TC). low-density lipoprotein cholesterol.(LDL-C), high density lipoprotein cholesterol (HDL-C), triglyceride (TG), liver function.renal function, the routine blood test and urine test were measured in the department of Clinical laboratory of Shandong Provincial Hospital. Results1. Comparisons of the general clinical data between the two groups: The differences in age, gender, body mass index (BMI), systolic blood pressure (SPB), diastolic blood pressure (DBP), TC HDL-C, LDL-C between DM group and NC group were not statistically significant (P>0.05), but,the FPG, TG and HbAlc in DM group including macrovascular subgroup(MV) and nonmacrovascular subgroup(NMV),were significantly higher than the NC group [(8.89±2.67) vs (5.12±0.41) mmol/l,(l.67±0.70) vs (0.93±0.30) mmol/1,(8.13±1.92) vs (5.12±0.53)%, P<0.01]. The two subgroups in DM group were different only in the course of disease.(P0.01).2. Comparisons of MT levels and MT a/ts ratio between the two groups: Serum MTt2levels and the ratio of MTClS in DM group were significantly lower than those in NC group[(57.4±27.6) vs(91.75±16.37)pg/ml,(2.37±0.99)vs(3.79±1.11) pg/ml, F<0.01],while the serum MT t8level between the two groops had no statistic difference (P>0.05). Serum MTt2levels and the ratio of MTa ts in MV group were apparently lower than those in NMV group[(41.00±15.94) vs(84.67±20.28)pg/mI,(3.32±0.58)vs(1.81±0.70) pg/ml, P<0.01],and there was no difference in the serum MTlS level between the two subgroups.3. Comparison of SOD and NO levels between the two groups: NC group serum SOD activity of the two time points of the DM group were significantly lower[(77.75±12.87) vs(96.88±12.37)u/mL,(72.13±12.51)vs(91.80±10.98) u/mL, P<0.01], and serum NO levels were significantly increased [(95.18±17.90)vs(82.84±20.U) umol/mL,(106.23±19.91)vs(81.75±6.28) umol/mL,P<0.05], The ratio of NOt2/t8was significantly lower(P<0.05). Of DM two sub-groups, serum SOD activity at the two time points in the MV group were significantly lower than[(71.70±7.04)vs(87.84±14.26) u/mL,(67.2l±10.24)vs(80.33±11.95) u/mL,P<0.01], serum NO content were significantly higher than in NMV*group [(100.69±18.73)vs(85.99±12.23) umol/mL (111.61±21.74)vs(97.27±12.67)umol/mL, P<0.05].4. Comparison of MT, SOD and NO between02:00and08:00in each group The serum MTti levels were significantly higher than MTts in DM group, NMV group, MV group and NC group[(57.4±27.6)vs(24.16±5.24)pg/ml,(84.67±20.28) vs(26.08±6.82)pg/ml,(41.00±15.94)vs(23.00±3.77)pg/ml,(91.75±16.37)vs(25.31±5.31)pg/ml,P<0.01]. The Serum SODt2activity was significantly higher than SODt8in DM group and NMV group [(77.75±12.87) vs(72.13±12.51)u/mL,(87.84±14.26)vs(80.33±11.95) u/mL,P<0.01], the differences of the serum SOD activity was not statistically significant between02:00and08:00in MV group and NC group.The serum NOt2content was significantly lower than NOt8[(95.18±17.90)vs(106.23±19.91)umol/mL,(85.99±12.23) vs(97.27±12.67) umol/mL,(100.69±18.73)vs(111.61±21.74) umol/mL, P <0.01] in DM group, the NMV group and the MV group, while in the NC group, the difference of the concentrations of serum NO between02:00and08:00were not statistically significant.5. The correlation analysis of serum MT levels and other index:We carried out the multi-element linear regression analysis to find out the relationship of t2&t8serum MT levels with FPG, TG, HbA1c, No, SOD and the disease course.The results showed that the MT t2was negatively correlated with disease duration,HbA1c,NOt2(P<0.05),positively with SOD,2(P<0.01),the multiple regression equation:MTt2=80.71-1.68disease duration-3.54of HbAlc-0.39of NO12,+0.72of SOD12. MTt8, however, was negatively correlated with NO18only (P<0.05), the multiple regression equations:MTt8=36.23-0.135NOt8.Conclusionl.Type2diabetes patients" serum melatonin levels are significantly reduced during night and exist circadian secretion rhythm disorders, it is more severe in patients with macrovascular disease, and it is not remarkable in patients without macrovascular disease, suggesting that melatonin may be a positive indicator in diabetic vascular disease.2. In type2diabetic patients, the serum melatonin levels correlate negatively with oxidative stress, suggesting that the down regulation of melatonin levels may be caused by oxidative stress. |
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