Relationship between circadian rhythm of blood pressure and target organ damage in essential hypertensive patients with type 2 diabetes mellitus

Objective To study the relationship between the circadian rhythm changes of blood pressure and target organ damage in essential hypertensive(EH) patients with type 2 diabetes mellitus(T2DM). Methods During Jun 2005 to Dec 2008,495 cases of outpatients and inpatients(121 male,374 female),aged from 40 to 79 ( 65.7±10.0)years were involved. Subjects were divided into 4 groups: essential hypertension(EH, n=199), (T2DM, n=73), essential hypertension with type 2 diabetes mellitus(EH+T2DM, n=110), and normal control (NC, n=113). Clinical data and ambulatory blood pressure monitoring indices of 24-hour mean systolic blood pressure(24hSBP),24-hour mean diastolic blood pressure(24hDBP), diurnal mean systolic blood pressure (dSBP), diurnal mean diastolic blood pressure(dDBP), nocturnal mean systolic blood pressure(nSBP), nocturnal mean diastolic blood pressure(nDBP), were compared among the four groups. The percentage differences between dSBP and nSBP(ΔSBP%), between dDBP and nDBP(ΔDBP%), and target organ damage among groups were analyzed. Results ①EH+T2DM patients showed decreased high density lipoprotein cholesterol (HDL-C) and increased triglyceride(TG)levels as compared with EH cases [(1.08±0.30) vs (1.20±0.31) mmol/L, (2.00±1.33) vs (1.56±0.88) mmol/L, all P0.01]. ②24hSBP and nSBP were significantly higher while 24hDBP and dDBP were lower in EH+T2DM group than those in EH group [24hSBP(141.2±12.5) vs (138.2±12.7)mmHg,P0.05; nSBP(137.5±9.7) vs (131.5±11.4)mm Hg; 24hDBP(76.1±9.3) vs (79.6±9.1)mm Hg; dDBP(77.43±9.8) vs (81.0±9.2)mm Hg, ]all P0.01]. ΔSBP% and ΔDBP% decreased significantly in EH+T2DM group compared to those in EH group, in T2DM group and in NC group(P0.01). ΔSBP% and ΔDBP% were significantly reduced in EH group compared with NC group(P0.01). ΔSBP% dropped significantly in EH group compared with that in T2DM group(P0.01). The incidence of target organ damage in EH+T2DM group was significantly higher compared to that in other groups(40.0% vs 31.5% vs 22.1% vs 8.8% (P0.01). ④ Age(OR=1.136, 95% CI 1.079-1.195, P=0.001) and kinds of disease (OR=1.662, 95% CI=1.138-2.428,P=0.009) were risk factors while ΔSBP% (OR=0.927,95% CI 0.877-0.979, P=0.007) was protective factor of target organ damage by logistic regression analysis.Conclusion Hypertension complicated with type 2 diabetes mellitus aggravated abnormality of the circadian rhythm of blood pressure and the degree of target organ damage.