Peripheral arterial compliance differs between races: comparison among Asian, Afro-Caribbeans, and white Caucasians with type 2 diabetes

Treatment of Diabetes in Older Adults: An Endocrine Society* Clinical Practice Guideline

OBJECTIVE

The objective is to formulate clinical practice guidelines for the treatment of diabetes in older adults.

CONCLUSIONS

Diabetes, particularly type 2, is becoming more prevalent in the general population, especially in individuals over the age of 65 years. The underlying pathophysiology of the disease in these patients is exacerbated by the direct effects of aging on metabolic regulation. Similarly, aging effects interact with diabetes to accelerate the progression of many common diabetes complications. Each section in this guideline covers all aspects of the etiology and available evidence, primarily from controlled trials, on therapeutic options and outcomes in this population. The goal is to give guidance to practicing health care providers that will benefit patients with diabetes (both type 1 and type 2), paying particular attention to avoiding unnecessary and/or harmful adverse effects.

Are zinc transporter type 8 antibodies a marker of autoimmune thyroiditis in non-obese adults with new-onset diabetes?

OBJECTIVE

The diagnosis of autoimmune diabetes in non-obese adults is based on the detection of glutamic acid decarboxylase autoantibodies (GADA), islet cell antibodies (ICA) and antibodies to tyrosine phosphatase (IA-2A). Zinc transporter 8 (ZnT8) has been identified as a new autoantigen in patients with type 1 diabetes mellitus. The coincidence of autoimmune thyroiditis (AITD) with diabetes is common; therefore, screening of TSH and thyroid peroxidase antibodies (ATPO) is recommended during the diagnosis of diabetes. In this study, we determined whether the occurrence of islet autoantibodies is associated with a positive titre of ATPO in newly diagnosed adult-onset autoimmune diabetic patients.

DESIGN AND METHODS

THE STUDY INVOLVED 80 NON-OBESE ADULTS AGED 44 (INTERQUARTILE RANGE (IQR): 37-51) years with a BMI of 24.0 (IQR: 22.2-26.0) kg/m(2) and new-onset diabetes. The markers of autoimmune diabetes (GADA, ICA, IA-2A and ZnT8A), TSH and thyroid peroxidase antibodies (ATPO) were evaluated.

RESULTS

IN THE STUDY POPULATION, 70% (N=56) OF THE SUBJECTS WERE POSITIVE FOR AT LEAST ONE OF THE FOUR ASSESSED MARKERS OF AUTOIMMUNE DIABETES (83.9% GADA, 62.5% ICA, 42.8% IA-2A AND 33% ZNT8A) AND 37.5% OF THE SUBJECTS WERE POSITIVE FOR ATPO. THE ZNT8A-POSITIVE SUBJECTS HAD HIGHER ATPO TITRES THAN THE ZNT8A-NEGATIVE SUBJECTS (172.7 (IQR: 0.36-410.4) vs 92.4 (IQR: 0-23.7) IU/ml, P=0.001). Based on the assessed islet autoantibodies, the occurrence of positive ZnT8A and GADA was found to be related to a positive titre of ATPO using logistic regression (OR=5.48, 95% CI: 1.65-18.14, P=0.006 and OR=3.42, 95% CI: 1.09-10.71, P=0.03 respectively).

CONCLUSIONS

In non-obese adults with new-onset diabetes, the presence of GADA and especially ZnT8 autoantibodies increases the risk of AITD.

Conduit vessel stiffness in British south Asians of Indian descent relates to 25-hydroxyvitamin D status

BACKGROUND

South Asians migrating to Northern latitudes are more susceptible to premature cardiovascular disease (CVD) than expected for given levels of blood pressure. Vitamin D deficiency is common in this group and may play an important role mediating vascular wall senescence in response to central pressure effects.

METHODS

A cross-sectional association study. South Asian and White European participants were randomly recruited from a population-based diabetes-screening programme. Carotid-femoral pulse wave velocity (cfPWV), biochemistry (25-hydroxyvitamin D, fasting glucose), anthropometrics, resting blood pressure and a physical activity measure (International Physical Activity Questionnaire) were measured under controlled conditions.

PARTICIPANTS

One hundred and thirty-two and 125 age-matched South Asians and White Europeans not taking vitamin D supplementation with a risk factor for diabetes but no overt CVD.

RESULTS

Age (mean south Asian: 55.7 vs. White European: 56.0 years), mean arterial pressure (MAP) and calculated CVD risk were similar in both groups. Unadjusted (cf)PWV (m/s) was higher (9.32 vs. 8.68 P = 0.001) and 25-hydroxyvitamin D (nmol/l) lower in (21.29 vs. 52.5 P < 0.001) south Asians. 25-Hydroxyvitamin D independently associated with cfPWV in multivariate modelling adjusted for age, MAP, sex, glucose, heart rate, vasoactive medication and south Asian ethnicity (R = 0.73, P = 0.004). 25-Hydroxyvitamin D but not physical activity was negatively correlated with cfPWV independent of south Asian ethnicity.

CONCLUSION

Aortic stiffness is increased in British Indo-Asians without vascular disease despite conventional risk profiles, which are comparable to age-matched white Europeans. This effect may be mediated by a greater pressure-dependent increase in stiffness in individuals with vitamin D insufficiency.

Arterial stiffness indices in healthy volunteers using non-invasive digital photoplethysmography

BACKGROUND

Increased arterial stiffness is a marker of cardiovascular damage, even in the absence of clinically apparent disease. It is likely to become an important clinical tool in cardiovascular risk assessment.

AIMS AND METHODS

We studied a group of healthy subjects and measured their arterial stiffness by digital photoplethysmography. We aimed to obtain a range of arterial stiffness values, and investigated the influence of age, gender, race, body mass index, fasting lipids and haemodynamic factors.

RESULTS

One hundred and fifty-two healthy subjects, aged between 18 and 67 years, on no medications and with no significant medical illnesses were recruited. The population was predominantly Caucasian (n = 112). Two measures of arterial stiffness were obtained: stiffness index (SI), a measure of large arterial stiffness, and reflection index (RI), a measure of small to medium-sized arterial stiffness. SI and RI were significantly correlated with age, total cholesterol, low-density lipoprotein-cholesterol, heart rate (HR), systolic blood pressure (SBP) and diastolic blood pressure (DBP). Race was a significant independent predictor of SI.

CONCLUSION

Digital photoplethysmography is a portable, operator-independent, reproducible and simple method of measuring arterial stiffness. Ranges of normality of arterial stiffness will depend on the individual's age, race, lipid levels, HR and blood pressure.

Increased arterial stiffness in remote Indigenous Australians with high risk of cardiovascular disease

OBJECTIVE

To assess central and peripheral arterial stiffness in Indigenous and European Australians with and without type 2 diabetes using applanation tonometry to obtain the augmentation index (AI) and pulse wave velocity (PWV).

METHODS

AI was assessed in 162 Indigenous Australians (60 with type 2 diabetes) participating in a population-based study and 121 Australians of European ancestry (38 with diabetes) of similar age and sex. PWV was assessed in a subgroup: n = 62 indigenous, n = 118 European participants.

RESULTS

The indigenous group had higher AI than the European group [mean (SD) 32 (12) versus 24 (12)%, P < 0.0001] and carotid-femoral PWV [8.4 (1.8) versus 7.1 (2.2) ms(-1), P < 0.0001]. There were no significant differences between groups regarding blood pressure and total cholesterol; however, indigenous individuals had higher fasting glucose, insulin, haemoglobin A1c, triglycerides, waist circumference (despite lower body mass index), and a higher prevalence of cigarette smoking. Fifty-five per cent of the variance in AI was explained on multiple regression analysis by age, sex, indigenous participant, heart rate, mean arterial pressure, height, triglycerides and waist circumference. Age, indigenous participant, heart rate, mean arterial pressure and antihypertensive medication explained 56% of the variance in PWV. Variables of the metabolic syndrome and smoking, C-reactive protein (CRP), homocysteine and heart rate clustered with indigenous status on factor analysis.

CONCLUSIONS

Indigenous Australians have higher indices of peripheral and central arterial stiffness than European Australians of similar age and sex. Factor analysis revealed that metabolic syndrome variables, smoking, CRP, homocysteine and heart rate clustered with 'indigenous participant' and may explain increased arterial stiffness in this group.

Ageing and vascular ageing

There is an age related decline in various physiological processes. Vascular ageing is associated with changes in the mechanical and the structural properties of the vascular wall, which leads to the loss of arterial elasticity and reduced arterial compliance. Arterial compliance can be measured by different parameters like pulse wave velocity, augmentation index, and systemic arterial compliance. There is evidence that arterial compliance is reduced in disease states such as hypertension, diabetes, and end stage renal failure. Changes in arterial compliance can be present before the clinical manifestation of cardiovascular disease. Pharmacological and non-pharmacological measures have been shown to improve arterial compliance. Arterial compliance may constitute an early cardiovascular risk marker and may be useful in assessing the effects of drugs on the cardiovascular system. Pharmacogenetics and genetics of arterial compliance in the future will improve our knowledge and understanding about vascular ageing.