Hypertension, Diabetes Type II, and Their Association: Role of Arterial Stiffness

Diabetes, cardiovascular disease and the microcirculation

Cardiovascular disease (CVD) is the leading cause of mortality in people with type 2 diabetes mellitus (T2DM), yet a significant proportion of the disease burden cannot be accounted for by conventional cardiovascular risk factors. Hypertension occurs in majority of people with T2DM, which is substantially more frequent than would be anticipated based on general population samples. The impact of hypertension is considerably higher in people with diabetes than it is in the general population, suggesting either an increased sensitivity to its effect or a confounding underlying aetiopathogenic mechanism of hypertension associated with CVD within diabetes. In this contribution, we aim to review the changes observed in the vascular tree in people with T2DM compared to the general population, the effects of established anti-diabetes drugs on microvascular outcomes, and explore the hypotheses to account for common causalities of the increased prevalence of CVD and hypertension in people with T2DM.

Arterial stiffness and dementia pathology: Atherosclerosis Risk in Communities (ARIC)-PET Study

OBJECTIVE

Arterial stiffness has been associated with evidence of cerebral small vessel disease (cSVD) and fibrillar β-amyloid (Aβ) deposition in the brain. These complex relationships have not been examined in racially and cognitively diverse cohorts.

METHODS

The Atherosclerosis Risk in Communities (ARIC)-Neurocognitive Study collected detailed cognitive testing for adjudication of dementia and mild cognitive impairment (MCI), brain MRI, and arterial stiffness by pulse wave velocity (PWV, carotid-femoral [cfPWV] and heart-carotid [hcPWV]). The ARIC-PET ancillary study added Aβ imaging using florbetapir ([18F]-AV-45) to obtain standardized uptake volume ratios and defined global Aβ-positivity as standardized uptake volume ratio >1.2. One-SD increase in PWV was related to brain volume, MRI-defined cSVD (e.g., cerebral microbleeds and white matter hyperintensity), and cortical Aβ deposition adjusted for age, body mass index, sex, race, and APOE ε4 status. We examined the cross-sectional relationships including interactions by race, APOE ε4 status, and cognition.

RESULTS

Among the 320 ARIC-PET participants (76 [5] years, 45% black, 27% MCI), greater central stiffness (hcPWV) was associated with greater Aβ deposition (odds ratio [OR] = 1.31, 95% confidence interval [CI] 1.01-1.71). Greater central stiffness (cfPWV) was significantly associated with having lower brain volumes in Alzheimer disease-susceptible regions (in mm3, β = -1.5 [0.7 SD], p = 0.03) and high white matter hyperintensity burden (OR = 1.6, 95% CI 1.2-2.1). Furthermore, cfPWV was associated with a higher odds of concomitant high white matter hyperintensity and Aβ-positive scans (OR = 1.4, 95% CI 1.1-2.1). These associations were strongest among individuals with MCI and did not differ by race or APOE ε4 status.

CONCLUSIONS

Arterial stiffness, measured by PWV, is an emerging risk factor for dementia through its repeated relationships with cognition, cSVD, and Aβ deposition.

Associations between Type 2 Diabetes Mellitus and Arterial Stiffness: A Prospective Analysis Based on the Maine-Syracuse Study

BACKGROUND

The aim of this study was to investigate prospective associations between type 2 diabetes mellitus status and the gold standard non-invasive method for ascertaining arterial stiffness, carotid femoral pulse wave velocity.

METHODS

The prospective analysis employed 508 community-dwelling participants (mean age 61 years, 60% women) from the Maine-Syracuse Longitudinal Study. Pulse wave velocity at wave 7 (2006-2010) was compared between those with type 2 diabetes mellitus at wave 6 (2001-2006) (n = 52) and non-diabetics at wave 6 (n = 456), with adjustment for demographic factors, cardiovascular risk factors and lifestyle- and pulse wave velocity-related factors.

RESULTS

Type 2 diabetes mellitus status was associated with a significantly higher pulse wave velocity (12.5 ± 0.36 vs. 10.4 ± 0.12 m/s). Multivariate adjustment for other cardiovascular risk factors and lifestyle- and pulse wave velocity-related variables did not attenuate the findings. The risk of an elevated pulse wave velocity (≥12 m/s) was over 9 times higher for those with uncontrolled type 2 diabetes mellitus than for those without diabetes (OR 9.14, 95% CI 3.23-25.9, p < 0.001).

CONCLUSIONS

Type 2 diabetes mellitus, particularly if uncontrolled, is significantly associated with risk of arterial stiffness later in life. Effective management of diabetes mellitus is an important element of protection from arterial stiffness.

Longitudinal Study of Hypertensive Subjects With Type 2 Diabetes Mellitus: Overall and Cardiovascular Risk

Despite adequate glycemic and blood pressure control, treated type 2 diabetic hypertensive subjects have a significantly elevated overall/cardiovascular risk. We studied 244 816 normotensive and 99 720 hypertensive subjects (including 7480 type 2 diabetics) attending medical checkups between 1992 and 2011. We sought to identify significant differences in overall/cardiovascular risk between hypertension with and without diabetes mellitus. Mean follow-up was 12.7 years; 14 050 all-cause deaths were reported. From normotensive to hypertensive populations, a significant progression in overall/cardiovascular mortality was observed. Mortality was significantly greater among diabetic than nondiabetic hypertensive subjects (all-cause mortality, 14.05% versus 7.43%; and cardiovascular mortality, 1.28% versus 0.7%). No interaction was observed between hemodynamic measurements and overall/cardiovascular risk, suggesting that blood pressure factors, even during drug therapy, could not explain the differences in mortality rates between diabetic and nondiabetic hypertensive patients. Using cross-sectional regression models, a significant association was observed between higher education levels, lower levels of anxiety and depression, and reduced overall mortality in diabetic hypertensive subjects, while impaired renal function, a history of stroke and myocardial infarction, and increased alcohol and tobacco consumption were significantly associated with increased mortality. Blood pressure and glycemic control alone cannot reverse overall/cardiovascular risk in diabetics with hypertension. Together with cardiovascular measures, overall prevention should include recommendations to reduce alcohol and tobacco consumption and improve stress, education levels, and physical activity.

Advances in the non-invasive assessment of vascular dysfunction in metabolic syndrome and diabetes: Focus on endothelium, carotid mechanics and renal vessels

AIM

The present paper is a selective review on the methodology and clinical significance of techniques to assess specifically endothelial function, carotid mechanics and renal vascular function, particularly in the light of vascular dysfunction in metabolic syndrome and type 2 diabetes.

DATA SYNTHESIS

Endothelial dysfunction appears to be earlier detectable in the microcirculation of patients with altered glucose metabolism, while it attains significance in the macrocirculation at more advanced disease stages. Smooth muscle cell dysfunction is now increasingly recognized to play a role both in the development of endothelial dysfunction and abnormal arterial distensibility. Furthermore, impaired glucose metabolism affects carotid mechanics through medial calcification, structural changes in extracellular matrix due to advanced glycation and modification of the collagen/elastin material stiffness. The assessment of renal vascular function by dynamic ultrasound or magnetic resonance imaging has recently emerged as an appealing target for identifying subtle vascular alterations responsible for the development of diabetic nephropathy.

CONCLUSIONS

Vascular dysfunction represents a major mechanism for the development of cardiovascular disease in patients with abnormal glucose metabolism. Hence, the currently available non-invasive techniques to assess early structural and vascular abnormalities merit recommendation in this population, although their predictive value and sensitivity to monitor treatment-induced changes have not yet been established and are still under investigation.

Nonalcoholic Fatty Liver Disease and Associated Metabolic Risks of Hypertension in Type 2 Diabetes: A Cross-Sectional Community-Based Study

The mechanisms facilitating hypertension in diabetes still remain to be elucidated. Nonalcoholic fatty liver disease (NAFLD), which is a higher risk factor for insulin resistance, shares many predisposing factors with diabetes. However, little work has been performed on the pathogenesis of hypertension in type 2 diabetes (T2DM) with NAFLD. The aim of this study is to investigate the prevalence of hypertension in different glycemic statuses and to analyze relationships between NAFLD, metabolic risks, and hypertension within a large community-based population after informed written consent. A total of 9473 subjects aged over 45 years, including 1648 patients with T2DM, were enrolled in this cross-sectional study. Clinical and biochemical parameters of all participants were determined. The results suggested that the patients with prediabetes or T2DM were with higher risks to have hypertension. T2DM with NAFLD had significantly higher levels of blood pressure, triglyceride, uric acid, and HOMA-IR than those without NAFLD. Data analyses suggested that hypertriglyceridemia [OR = 1.773 (1.396, 2.251)], NAFLD [OR = 2.344 (1.736, 3.165)], hyperuricemia [OR = 1.474 (1.079, 2.012)], and insulin resistance [OR = 1.948 (1.540, 2.465)] were associated with the higher prevalence of hypertension independent of other metabolic risk factors in type 2 diabetes. Further studies are needed to focus on these associations.

Single nucleotide polymorphism of adiponectin +276 G/T is associated with the susceptibility to essential hypertension in a Turkish population

BACKGROUND

It is well known that arterial stiffness is associated with hypertension. Recent studies have shown that adiponectin +276 G/T, ACE I/D, AGTR1 A1166C, and eNOS E298D polymorphisms are likely to be risk factors for arterial stiffness. In this study, we aimed to investigate possible associations between these single-nucleotide polymorphisms (SNPs) and essential hypertension in a Turkish population.

METHODS

The study population consisted of 170 patients who were diagnosed with essential hypertension and 170 sex- and age-matched controls. Genotyping of adiponectin +276 G/T, ACE I/D, AGTR1 A1166C, and eNOS E298D SNPs were performed using real-time polymerase chain reaction and commercially produced kits.

RESULTS

The percentage of the adiponectin +276 T allele carriers was significantly higher in the patients with hypertension (33%) than in the controls (25%, p < 0.011). Through multiple logistic regression analysis, the adiponectin +276 T allele carrier was found to be associated with an increased risk of hypertension (TT vs. GG and TG: odds ratio = 3.318, p = 0.014, 95% confidence interval: 1.269-8.678). The genotype distributions or allelic frequencies of ACE I/D, AGTR1 A1166C, and eNOS E298D SNPs did not significantly differ between the patients with hypertension and the controls.

CONCLUSION

The present study demonstrated that the adiponectin +276 G/T SNP is likely to be a risk factor for essential hypertension in a Turkish population.