Glycated haemoglobin and cardiovascular risk factors in Chinese subjects with normal glucose tolerance

Lipid profiles and their relation to glycemic control in Saudi Arabia: The role of altitudes and environmental factor

Background

The height from sea levels, environmental factors, human-environment interactions, and lifestyle significantly influence the lipid profile and glycemic control of a population.

Objective

This study aims to explore the influence of altitude on lipid profiles and glycemic control among the Saudi population at sea level and high altitude.

Methods

In this retrospective cross-sectional study, a large dataset of patients of both gender and over 30 years old attending internal medicine clinics from two different regions at different heights from sea level, Jeddah (sea level) and Asir region (high altitudes) and referred to commercial laboratories for glycated haemoglobin (HbA1c) and lipids profile.

Results

Compared to the Asir region, the Jeddah region had significantly higher mean values for fasting blood sugar (FBG), total cholesterol (TC), low-density lipoprotein (LDL-C), and triglycerides (TG) (P < 0.05). Every 1 mg/dL increase in FBG results in a 0.662 mg/dL increase in TG from the Jeddah region. However, it was a 0.318 mg/dL increase in TG from the Asir region. HbA1c demonstrated a significant (P < 0.05) strong positive correlation with TC, low-density lipoprotein cholesterol (LDL-C), triglycerides (TG), and lipid ratio. FBG levels were also associated with a high level of TC/HDL-C (β = 0.137 95% confidence interval [CI]: 0.11-0.21; P < 0.05), LDL-C/high-density lipoprotein cholesterol (HDL-C) (β = 0.50; 95% CI: 0.31-1.49; P < 0.05), and TG/HDL-C (β = 0.14; 95% CI = 0.12-0.15; P < 0.05) in Jeddah region. However, significantly high blood pressure was observed in the population from high altitudes.

Conclusion

Our results demonstrated a significant positive correlation between lipid profile and glycemic control with high prevalence at sea level.

Correlates of poor glycemic control among patients with diabetes initiating hemodialysis for end-stage renal disease

Background

Maintaining tight glycemic control is important for prevention of diabetes-related outcomes in end-stage renal disease patients with diabetes, especially in light of their poor prognosis. This study aimed to determine factors associated with poor glycemic control among U.S. patients with diabetes mellitus initiating hemodialysis for end-stage renal disease.

Methods

Using data from the U.S. Renal Data System, electronic health records of a large national dialysis provider, and U.S. Census data, we performed a cross-sectional multivariable Poisson regression analysis to characterize risk factors associated with poor glycemic control, defined as glycated hemoglobin (HbA1c) >7 vs. ≤7 %, in adult patients with diabetes who initiated hemodialysis at an outpatient facility between 2006 and 2011.

Results

Of 16,297 patients with diabetes, 21.2 % had HbA1c >7 %. In multivariable analysis, younger patients, patients of Native American race, and those of Hispanic ethnicity had higher prevalence of poor glycemic control. Independent correlates of poor glycemic control further included higher platelet count, white blood cell count, and ferritin; higher body mass index, systolic blood pressure, total cholesterol and triglyceride concentrations; lower HDL and albumin concentrations; lower normalized protein catabolic rate; and higher estimated glomerular filtration rate at initiation of dialysis (all P < 0.05). No independent associations were found with area-level socioeconomic indicators. Occurrence of diabetes in patients <40 years of age, a proxy for type 1 diabetes, was associated with poor HbA1c control compared with that in patients ≥40 years of age, which was classified as type 2 diabetes. These findings were robust to the different outcome definitions of HbA1c >7.5 % and >8 %.

Conclusion

In this cohort of incident end-stage renal disease patients with diabetes, poor glycemic control was independently associated with younger age, Native American race, Hispanic ethnicity, higher body mass index, and clinical risk factors including atherogenic lipoprotein profile, hypertension, inflammation, and markers indicative of malnutrition and a more serious systemic disease.

Is HbA1c a risk factor for type 2 diabetic subjects without macro and micro vascular complications?

OBJECTIVE

Our study attempted to evaluate the diagnostic value of HbA1c in predicting diabetic dyslipidemia and cardiovascular diseases (CVD).

METHODS

Study comprised 229 subjects (156 males and 73 females) with diabetic dyslipidemia without any micro and macro vascular disorders. Fasting blood samples were taken to analyse biochemical parameters like HbA1c, sugar and lipid profile.

RESULTS

The HbA1c levels did not differ much between males (6.96 ± 1.11) and females (7.01 ± 1.19). HbA1c demonstrated a positive significant correlation with cholesterol, LDL and a negative significant correlation with HDL. Patients with HbA1c >7.0% had significantly higher value of cholesterol, LDL when compared with <7.0%.

CONCLUSIONS

The findings of this study clearly suggest that HbA1c endures the ability of predicting CVD risk in the diabetic patients without any micro and macro vascular disorder. Therefore study recommends using HbA1c as a marker for predicting the risk of developing CVD.

Utility of hemoglobin A(1c) for diagnosing prediabetes and diabetes in obese children and adolescents

OBJECTIVE

Hemoglobin A(1c) (A1C) has emerged as a recommended diagnostic tool for identifying diabetes and subjects at risk for the disease. This recommendation is based on data in adults showing the relationship between A1C with future development of diabetes and microvascular complications. However, studies in the pediatric population are lacking.

RESEARCH DESIGN AND METHODS

We studied a multiethnic cohort of 1,156 obese children and adolescents without a diagnosis of diabetes (male, 40%/female, 60%). All subjects underwent an oral glucose tolerance test (OGTT) and A1C measurement. These tests were repeated after a follow-up time of ∼2 years in 218 subjects.

RESULTS

At baseline, subjects were stratified according to A1C categories: 77% with normal glucose tolerance (A1C <5.7%), 21% at risk for diabetes (A1C 5.7-6.4%), and 1% with diabetes (A1C >6.5%). In the at risk for diabetes category, 47% were classified with prediabetes or diabetes, and in the diabetes category, 62% were classified with type 2 diabetes by the OGTT. The area under the curve receiver operating characteristic for A1C was 0.81 (95% CI 0.70-0.92). The threshold for identifying type 2 diabetes was 5.8%, with 78% specificity and 68% sensitivity. In the subgroup with repeated measures, a multivariate analysis showed that the strongest predictors of 2-h glucose at follow-up were baseline A1C and 2-h glucose, independently of age, ethnicity, sex, fasting glucose, and follow-up time.

CONCLUSIONS

The American Diabetes Association suggested that an A1C of 6.5% underestimates the prevalence of prediabetes and diabetes in obese children and adolescents. Given the low sensitivity and specificity, the use of A1C by itself represents a poor diagnostic tool for prediabetes and type 2 diabetes in obese children and adolescents.

Haemoglobin A1c levels and subsequent cardiovascular disease in persons without diabetes: a meta-analysis of prospective cohorts

AIMS/HYPOTHESIS

The aim of this meta-analysis was to determine the relationship between HbA(1c) levels and subsequent cardiovascular outcomes in individuals without diabetes.

METHODS

We searched Medline, Embase and Scopus from initiation of the study until the end of 2009. One reviewer searched and another verified findings. Data were extracted by one reviewer and verified by another. We accepted prospective studies in any language reporting three or more quartiles for HbA(1c) levels. Within quartiles, authors must have presented both numbers of patient-years at risk and cardiovascular outcomes. Outcomes per person-time at risk were regressed on average HbA(1c) values using Poisson regression. We pooled β coefficients using Cochran's semi-weighted (inverse variance) random-effects model. Study quality was assessed using the Downs-Black scale.

RESULTS

We investigated 16 datasets (nine for total cardiovascular events and seven for death) from five papers with 44,158 patients (44% men) over 404,899 patient-years of follow-up. There were 1,366 cardiovascular deaths (3.1%; 3.37/1,000 person-years) and 2,142 cardiovascular events (4.9%; 5.29/1,000 person-years). The overall meta-analytic β coefficients were 0.720 (95% CI 0.307-1.133) and 0.757 (95% CI 0.382-1.132) for cardiac death and events, respectively. Compared with the baseline value of 0.0427, an HbA(1c) level of 0.05 was associated with a relative risk for cardiovascular death of 1.13 (95% CI 1.05-1.21), a 0.06 value with 1.34 (95% CI 1.13-1.58), and a 0.07 HbA(1c) with relative risk 1.58 (95% CI 1.22-2.06). Results for total cardiovascular events were similar. The average study quality was 0.7 (70%).

CONCLUSIONS/INTERPRETATION

We conclude that HbA(1c) was significantly associated with cardiovascular events and deaths in persons without diabetes.

Alterations in HbA(1c) with advancing age in subjects with normal glucose tolerance: Chandigarh Urban Diabetes Study (CUDS)

OBJECTIVE

To study the alterations in HbA(1c) with advancing age in subjects with normal glucose tolerance.

METHODS

Community-based cross-sectional study involving 2368 subjects aged ≥ 20 years from Chandigarh, India. All the subjects underwent an oral glucose tolerance test with 75 g anhydrous glucose and were classified as having normal glucose tolerance, pre-diabetes or diabetes according to World Health Organization 1999 criteria. HbA(1c) was measured on a National Glycohemoglobin Standardization Program-certified Bio-Rad D-10 system and the data were available for 1972 subjects.

RESULTS

Out of 1972 subjects, 1317 (67%) subjects had normal glucose tolerance. There was a significant positive correlation between mean HbA(1c) and age in these subjects (r = 0.308, P(trend) < 0.001). The increase in HbA(1c) with each advancing year was 0.01% above the age of 20 years and corrected HbA(1c) (%) for age was 5.09 + 0.01 (age). The 95th percentile of HbA(1c) exceeded 6.5% (48 mmol/mol) (the American Diabetes Association cut-off for diagnosis of diabetes) in subjects aged ≥ 70 years. A significantly higher number (6.5%, 21/325) of subjects had HbA(1c) of ≥ 6.5% (48 mmol/mol) in those above the age of 50 years compared with those below the age of 50 years (1.7%, 17/992) in the group with normal glucose tolerance (P < 0.001). On multivariate regression analysis, after adjusting for BMI, fasting plasma glucose and 2-h plasma glucose post-glucose load, the correlation of HbA(1c) with age still remained significant (r = 0.241, P < 0.01).

CONCLUSION

HbA(1c) increases with advancing age independent of glycaemia, suggesting caution when seeking to achieve the recommended HbA(1c) targets in the elderly population.

Obstructive sleep apnea is highly prevalent and correlates with impaired glycemic control in consecutive patients with the metabolic syndrome

Obstructive sleep apnea (OSA) and the metabolic syndrome (MS) are independently associated with increased cardiovascular risk. The objective of the present study was to determine the prevalence of OSA among consecutive patients with MS and to determine whether OSA is associated with impaired glycemic control. Fifty consecutive patients with a recent diagnosis of MS and no previous diagnosis of OSA underwent a polysomnography and anthropometric and laboratory measurements. The prevalence of OSA (apnea-hypopnea index >or=15 events per hour of sleep) was 68% and in the same range of all other individual components of MS. Moreover, OSA was associated with increased levels of glucose (P=.03) and glycosylated hemoglobin (P=.03) but not with body mass index (P=.30). Glycosylated hemoglobin was independently associated with glucose (P<.001) and apnea-hypopnea index (P=.03). The prevalence of OSA is in the same range as all the individual components of MS and is independently associated with impaired glycemic control.

Effect of aging on A1C levels in individuals without diabetes: evidence from the Framingham Offspring Study and the National Health and Nutrition Examination Survey 2001-2004

OBJECTIVE

Although glycemic levels are known to rise with normal aging, the nondiabetic A1C range is not age specific. We examined whether A1C was associated with age in nondiabetic subjects and in subjects with normal glucose tolerance (NGT) in two population-based cohorts.

RESEARCH DESIGN AND METHODS

We performed cross-sectional analyses of A1C across age categories in 2,473 nondiabetic participants of the Framingham Offspring Study (FOS) and in 3,270 nondiabetic participants from the National Health and Nutrition Examination Survey (NHANES) 2001-2004. In FOS, we examined A1C by age in a subset with NGT, i.e., after excluding those with impaired fasting glucose (IFG) and/or impaired glucose tolerance (IGT). Multivariate analyses were performed, adjusting for sex, BMI, fasting glucose, and 2-h postload glucose values.

RESULTS

In the FOS and NHANES cohorts, A1C levels were positively associated with age in nondiabetic subjects. Linear regression revealed 0.014- and 0.010-unit increases in A1C per year in the nondiabetic FOS and NHANES populations, respectively. The 97.5th percentiles for A1C were 6.0% and 5.6% for nondiabetic individuals aged <40 years in FOS and NHANES, respectively, compared with 6.6% and 6.2% for individuals aged >or=70 years (P(trend) < 0.001). The association of A1C with age was similar when restricted to the subset of FOS subjects with NGT and after adjustments for sex, BMI, fasting glucose, and 2-h postload glucose values.

CONCLUSIONS

A1C levels are positively associated with age in nondiabetic populations even after exclusion of subjects with IFG and/or IGT. Further studies are needed to determine whether age-specific diagnostic and treatment criteria would be appropriate.

Clinical significance of HbA1c as a marker of circulating lipids in male and female type 2 diabetic patients

Diabetic patients with accompanied (but often unnoticed) dyslipidemia are soft targets of cardiovascular deaths. An early intervention to normalize circulating lipids has been shown to reduce cardiovascular complications and mortality. Glycated hemoglobin (HbA(1c)) is a routinely used marker for long-term glycemic control. This investigation is an attempt to evaluate the diagnostic value of HbA(1c) in predicting diabetic dyslipidemia. Venous blood samples were collected from 2,220 type 2 diabetic patients (ages, 35-91 years; male/female ratio, 1.07). The sera were analyzed for HbA(1c), fasting blood glucose (FBG), total cholesterol, triglycerides, high-density lipoprotein cholesterol (HDL) and low-density lipoprotein cholesterol (LDL). The levels of HbA(1c) did not differ significantly between males (8.33 +/- 0.06%) and females (8.47 +/- 0.07%), whereas female patients had significantly higher FBG (10.01 +/- 0.13 mmol/l) than males (9.31 +/- 0.11 mmol/l). HbA(1c) showed direct and significant correlations with cholesterol, triglycerides and LDL and inverse correlation with HDL. Female diabetic patients had significantly higher levels of serum cholesterol (5.42 +/- 0.03 vs. 5.18 +/- 0.03 mmol/l) and HDL (1.32 +/- 0.01 vs. 1.12 +/- 0.01 mmol/l) as compared to males. There was no significant difference in triglycerides and LDL between the two genders. Older patients (>70 years) had significantly lower FBG, cholesterol, triglycerides and LDL. There was a linear and significant increase in triglycerides in the patients of both genders with impaired glycemic control. Both male and female patients with worse glycemic control (HbA(1c) > 9%) had significantly high cholesterol and LDL levels. Serum HDL showed a significant and inverse relationship with uncontrolled hyperglycemia in females but not in males. These findings clearly suggest that HbA(1c) can provide valuable supplementary information about the extent of circulating lipids besides its primary role in monitoring long-term glycemic control. Further studies are warranted to reinforce the potential of HbA(1c) as a biomarker for screening of high-risk diabetic patients.

Association of A1C with cardiovascular disease and metabolic syndrome in Asian Indians with normal glucose tolerance

OBJECTIVE

This study examines the association of A1C with cardiovascular disease (CVD) risk factors, coronary artery disease (CAD), and metabolic syndrome in Asian Indians with normal glucose tolerance (NGT).

RESEARCH DESIGN AND METHODS

This cross-sectional study recruited subjects from phase III of the Chennai Urban Rural Epidemiology Study (CURES), an epidemiological study in a representative population of Chennai (formerly Madras) in South India, conducted between January 2003 and June 2004. Included were 1,644 subjects with NGT, i.e., fasting plasma glucose <100 mg/dl (5.6 mmol/l) and 2-h postload plasma glucose <140 mg/dl (7.8 mmol/l). A1C was measured using the Biorad Variant machine. Metabolic syndrome was defined based on modified Adult Treatment Panel III guidelines.

RESULTS

The mean +/- SD A1C value in the study cohort was 5.5 +/- 0.4%. A1C showed a significant association with BMI (beta = 0.017, P < 0.001), systolic (beta = 0.002, P = 0.028) and diastolic (beta = 0.202, P = 0.017) blood pressure, waist circumference (beta = 0.007, P < 0.001), serum cholesterol (beta = 0.002, P < 0.001), triglycerides (beta = 0.001, P < 0.001), LDL cholesterol (beta = 0.002, P < 0.001), fasting insulin (beta = 0.009, P < 0.001), and homeostasis model assessment of insulin resistance (beta = 0.047, P < 0.001) after adjusting for age and sex. Regression analysis showed that A1C had a strong association with metabolic syndrome that persisted after adjusting for age and sex (odds ratio [OR] 2.9 [95% CI 2.08-4.00]; P < 0.001). A1C also had a strong association with CAD (2.6 [1.23-5.63]; P = 0.01), but the significance was lost when adjusted for age and sex.

CONCLUSIONS

There is a strong association of A1C with prevalent CVD risk factors in Asian-Indian subjects with NGT.

Age, body mass index and 2-hour plasma glucose are the major determinants of blood pressure in Chinese women newly diagnosed to have glucose intolerance

Hypertension and diabetes frequently coexist and greatly increase cardiovascular risk. There are relatively few data on the relationship between blood pressure and plasma glucose in newly diagnosed diabetic subjects especially in Chinese. We examined the glycaemic status, blood pressure profiles and other clinical and biochemical characteristics in 1298 Hong Kong Chinese women. These women were referred to the Diabetes and Endocrine Center of the Prince of Wales Hospital for screening of diabetes. The reasons for referral included a positive family history of diabetes or a history of gestational diabetes. Of the 1298 subjects, 836 (64.4%) had normal oral glucose tolerance test, 284 (21.9%) had impaired glucose tolerance and 178 (13.7%) had diabetes. Compared to non-diabetic subjects, the odds ratio (95% confidence interval) of having hypertension in subjects with impaired glucose tolerance or diabetes were 2.83 (1.90, 4.23) (P<0.001) and 5.94 (3.94, 8.96) (P<0.001), respectively. When analyzed as a continuous variable by age-adjusted partial correlation coefficients, systolic blood pressure was correlated with body mass index, fasting and 2-h plasma glucose, while diastolic blood pressure was correlated with body mass index. Using age, body mass index, fasting and 2-h plasma glucose, glycated hemoglobin, cholesterol, triglyceride and smoking as independent variables in multivariate analysis, hypertension was independently related to age, body mass index and 2-h plasma glucose. In conclusion, increased blood pressure was common in Hong Kong Chinese women who were newly diagnosed to have glucose intolerance. Apart from age and body mass index, plasma glucose was an independent determinant for blood pressure in these subjects.