Standardization of HbA1c measurements--a consensus statement

Mean Platelet Volume and Platelet Distribution Width Correlate with Microvascular Complications in Egyptian People with Type 2 Diabetes Mellitus

BACKGROUND

Type 2 diabetes is a part of metabolic syndrome associated with a higher risk of vascular complications. Diabetes is characterized by changes in platelet morphology, function, and platelet hyperactivity so, it's considered a prothrombotic condition. Morbidity and mortality in people with type 2 diabetes-related to micro and macrovascular complications. Novel biomarkers are needed to identify and treat people at higher risk.

OBJECTIVE

The main objective of this controlled cross-sectional study was to evaluate Platelet volume indices (PVI) in subjects with type 2 diabetes with and without complications in comparison to subjects without diabetes.

METHODS

Hundred and thirty-five subjects aged from 35 to 60 years were subdivided into 3 groups. Group A includes 55 subjects with type 2 diabetes with complications. Group B includes 45 subjects with type 2 diabetes without complications. Group C includes 35 normal healthy subjects. Detailed clinical history was taken. Also, PVI, fasting blood glucose (FBG), hemoglobin A1c, and creatinine were obtained.

RESULTS

Mean Platelet Volume (MPV), Platelet Distribution Width (PDW), Plateletcrit (PCT), and Platelet large cell ratio (P-LCR) were significantly higher among subjects with retinopathy, nephropathy, and neuropathy than other subjects with diabetes who didn't develop complications (P<0.001). At cutoff value > 11.9 fL, MPV have diagnostic sensitivity 80% and specificity 97.8%. Whereas PDW >16.9fL has a sensitivity of 74.5% and specificity of 100% for diabetic microvascular complications (retinopathy, nephropathy, and neuropathy).

CONCLUSION

MPV and PDW may be considered as possible biomarkers for the early detection of diabetic microvascular complications.

Ambient air pollution exposure association with diabetes prevalence and glycosylated hemoglobin (HbA1c) levels in China. Cross-sectional analysis from the WHO study of AGEing and adult health wave 1

Over the past decades, air pollution has become one of the critical environmental health issues in China. The present study aimed to evaluate links between ambient air pollution and the prevalence of type 2 diabetes mellitus (T2DM) and the levels of glycosylated hemoglobin (HbA1c). A multilevel linear and logistic regression was used to assess these associations among 7,770 participants aged ≥50 years from the WHO Study on global AGEing and adult health (SAGE) in China in 2007-2010. The average exposure to each of pollutants (particulate matter with an aerodynamic diameter of ≤10 μm/≤2.5 μm/≤1 μm [PM₁₀/PM_2.5/PM₁] and nitrogen dioxide [NO₂]) was estimated using a satellite-based spatial statistical model. In logistic models, a 10 µg/m³ increase in PM₁₀ and PM_2.5 was associated with increased T2DM prevalence (Prevalence Odds Ratio, POR: 1.27; 95% CI: 1.11, 1.45 and POR: 1.23; 95% CI: 1.03, 1.46). Similar increments in PM₁₀, PM_2.5, PM₁ and NO₂ were associated with increase in HbA1c levels of 1.8% (95% CI: 1.3, 2.3), 1.3% (95% CI: 1.1, 1.5), 0.7% (95% CI: 0.1, 1.3), and 0.8% (95% CI: 0.4, 1.2), respectively. In a large cohort of older Chinese adults, air pollution was liked to both higher T2DM prevalence and elevated HbA1c levels.

Platelet volume indices as predictive biomarkers for diabetic complications in Type 2 diabetic patients

BACKGROUND:

Platelet volume indices (PVI) such as mean platelet volume (MPV), platelet distribution width (PDW), and platelet-large cell ratio (P-LCR) are the indicators of increased platelet activity and can be considered as potential biomarkers for diabetic complications.

PURPOSE:

To study PVI in Type 2 diabetics with and without complications in comparison to nondiabetic patients.

MATERIALS AND METHODS:

A case–control study was conducted on 300 Type 2 diabetics and 200 nondiabetics. Detailed clinical history regarding duration, hypertension, and complications was taken. PVI was obtained using automated cell counter. Fasting blood glucose, hemoglobin A1c, lipid profile, creatinine were also obtained. Diabetics were further categorized into patients with complications and without complications. Statistical analysis was performed by Statistical Package for the Social Sciences Version 17 (Chicago, IL) Student's t-test and ANOVA test.

RESULTS:

Platelet count was significantly decreased in diabetics (P = 0.005). MPV was significantly increased in diabetic patients with complications as compared to diabetics without complications and nondiabetic group (P < 0.0001). PDW showed statistically significant difference between diabetics with and without complications and nondiabetics (P < 0.0001). However, no statistically significant difference was observed in platelet-large cell ratio (P-LCR) among all the three study groups. We found statistically significant correlation of MPV with diabetic retinopathy (P = 0.000), nephropathy (P = 0.005), and diabetic foot (P = 0.048). PDW was significantly increased in diabetic retinopathy (P = 0.035) and nephropathy (P = 0.007). P-LCR had no statistically significant correlation with diabetic complications.

CONCLUSION:

MPV and PDW are predictive biomarkers of diabetic vascular complications. They are more significant in microvascular complications than macrovascular complications.

Point-of-care hemoglobin A1c testing in postmortem examination

Glycated hemoglobin (HbA1c) is a good marker for monitoring glycemic control, and an elevated postmortem blood HbA1c level might indicate poor glycemic control during the antemortem period. The HbA1c level can be measured as a point-of-care (POC) test. In forensic medicine, POC testing is useful for performing autopsies and postmortem inspections since POC testing is both rapid and efficient. This study evaluated HbA1c levels in the capillary and cardiac venous blood of postmortem specimens as well as the usefulness of evaluating HbA1c levels as POC testing in postmortem examinations. For HbA1c testing performed on 103 autopsy cases, a portable SD A1cCare (test) was used for the POC testing, along with a Cobas Integra 800 (comparative). There was a strong correlation between HbA1c levels from postmortem capillary and cardiac venous blood (regression equation, 0.000 + 1.000×), and between HbA1c levels of cardiac venous blood measured using the portable SD A1cCare as a POC test and the Cobas Integra 800 (regression equation, -0.532 + 1.080×). HbA1c levels measured up to 4 weeks following the autopsy with the SD A1cCare had a tendency to decline. The author concluded that HbA1c POC testing can be used during postmortem inspection and during autopsy to accurately identify patients who had uncontrolled diabetes mellitus.

Prevalence, glucose control and relative survival of people with Type 2 diabetes in the UK from 1991 to 2013

AIMS

To characterize the prevalence of Type 2 diabetes between 1991 and 2013 in the UK and to determine whether corresponding glucose control and survival had changed in the diabetic population during this period.

METHODS

For this retrospective cohort study, people diagnosed with Type 2 diabetes between 1991 and 2013 were identified from the Clinical Practice Research Datalink (CPRD) and the annual point prevalence calculated. Mean HbA_1c by year was estimated. The Cox proportional hazards model was used to calculate the risk of all-cause mortality by year for incident cases of Type 2 diabetes treated with glucose-lowering therapy.

RESULTS

Crude prevalence of diagnosed Type 2 diabetes increased from 1.32% [95% confidence interval (95% CI) 1.30% to 1.34%] in 1991 to 4.54% (4.52% to 4.56%) in 2013. Mean HbA_1c for people with diagnosed Type 2 diabetes was 71 mmol/mol (8.6%) in 1991, 59 mmol/mol (7.5%) in 2003 and 58 mmol/mol (7.5%) in 2013. For diagnosed Type 2 diabetes treated with glucose-lowering therapy, when compared with 1991, the hazard ratio for all-cause mortality was 0.33 (0.27-0.41) in 2013.

CONCLUSION

The prevalence of diagnosed Type 2 diabetes trebled in the UK between 1991 and 2013. Improved survival in people with diagnosed Type 2 diabetes is likely to account, at least in part, for the increase in prevalence observed.

Association between HbA1c and carotid atherosclerosis among elderly Koreans with normal fasting glucose

Aim

We examined whether glycated haemoglobin (HbA1c) is associated to carotid atherosclerosis in an elderly Korean population with normal fasting glucose.

Methods

Using data from the Korean Urban Rural Elderly study, we conducted a cross-sectional analysis of 1,133 participants (335 men and 798 women) with a mean age of 71.8 years. All participants had fasting blood glucose less than 100mg/dL (5.6 mmol/L) and HbA1c level below 6.5% (48 mmol/mol). They were also free from a history of cardiovascular disease, known type 2 diabetes mellitus or use of anti-diabetes medications. Carotid atherosclerosis was assessed by intima-media thickness (IMT) using ultrasonography. The association between HbA1c and carotid IMT was investigated using multivariable linear regression analysis.

Results

HbA1c levels were independently and positively associated with carotid IMT (β = 0.020, p = 0.045) after adjusting for sex, age, body mass index, systolic blood pressure, diastolic blood pressure, triglyceride, LDL cholesterol, smoking and alcohol intake. However, fasting insulin and glucose levels were not associated with carotid IMT.

Conclusion

HbA1c levels were positively associated with carotid atherosclerosis, as assessed by carotid IMT, in an elderly population with normoglycemia. Our study suggested that higher HbA1c level is an effective and informative marker of carotid atherosclerosis in an elderly population.

Continuous subcutaneous insulin infusion versus multiple daily injections of insulin for pregnant women with diabetes

BACKGROUND

Diabetes results in a rise in blood glucose above normal physiological levels; if untreated this may cause damage to many systems including the cardiovascular and renal systems. Pregnancy increases resistance to insulin action; for those women who have pre-gestational diabetes, this results in an increasing insulin requirement. There are several methods of administering insulin. Conventionally, insulin has been administered subcutaneously, formally referred to as intensive conventional treatment, but now more usually referred to as multiple daily injections (MDI). An alternative method of insulin administration is the continuous subcutaneous insulin infusion pump (CSII).

OBJECTIVES

To compare CSII with MDI of insulin for pregnant women with pre-existing and gestational diabetes.

SEARCH METHODS

We searched the Cochrane Pregnancy and Childbirth Group's Trials Register (31 March 2016) and reference lists of retrieved studies.

SELECTION CRITERIA

Randomised trials comparing CSII with MDI for pregnant women with diabetes.

DATA COLLECTION AND ANALYSIS

Three review authors independently assessed studies and two review authors extracted data. Disagreements were resolved through discussion with the third author. We assessed the quality of the evidence using the GRADE approach.

MAIN RESULTS

We included five single-centre trials (undertaken in Italy) with 153 women and 154 pregnancies in this review.There were no clear differences in the primary outcomes reported between CSII and MDI in the included trials: caesarean section (risk ratio (RR) 1.09, 95% confidence interval (CI) 0.66 to 1.77; three trials, 71 women, evidence graded very low), large-for-gestational age (RR 4.15, 95% CI 0.49 to 34.95; three trials, 73 infants; evidence graded very low), and perinatal mortality (RR 2.33, 95% CI 0.38 to 14.32; four trials, 83 infants, evidence graded very low). Other primary outcomes were not reported in these trials (hypertensive disorders of pregnancy, development of type 2 diabetes, composite outcome of serious neonatal outcomes, and neurosensory disability).There was no clear evidence of differences in the maternal secondary outcomes: maternal weight gain during pregnancy, 24 hour mean blood glucose in each trimester, mean maternal HbA1c in each trimester, maternal hypoglycaemia, and maternal hyperglycaemia. The included studies did not report several GRADE outcomes: perineal trauma, return to pre-pregnancy weight, postnatal depression, induction of labour. Many maternal secondary outcomes were also not reported.In two trials, including a total of 61 infants, CSII was associated with an increase in mean birthweight compared with MDI (mean difference (MD) 220.56 g, 95% CI -2.09 g to 443.20 g; P = 0.05). However, the large CI including anything from a small reduction to an increase in mean birthweight and the lack of a difference in macrosomia rate (RR 3.20, CI 0.14 to 72.62; two trials, 61 infants) suggests uncertainty. Large-for-gestational age (see above), andsmall-for-gestational age also suggests uncertainty of effect. No significant differences were found in: gestation at delivery, preterm birth < 37 weeks' gestation, preterm birth < 32 weeks' gestation, neonatal hypoglycaemia (evidence graded very low), respiratory distress syndrome, neonatal hyperbilirubinaemia, and fetal anomaly. There were no data reported on many important infant outcomes, including the GRADE outcomes adiposity and diabetes. There was no follow-up of infants in childhood or adulthood, so longer-term outcomes were not reported.The only outcome reported for use of health service resources wasmaternal days hospitalised, which did not show a difference between groups in the small number of women included (MD 9.40, CI -6.04 to 24.84; one trial, 10 women).The methods used by the trials were poorly reported, for example although blinding of participants and clinicians regarding intervention allocation is impossible, it is possible to blind assessors and this along with other aspects of trial methods was not reported, which means that the trials are at an unclear or high risk of bias. We do not know if the women who participated were representative, and therefore if the results can be generalised. Most GRADE outcomes were not reported. For the GRADE outcomes that were reported, our assessment was that the evidence is very low quality (caesarean section, large-for-gestational age, perinatal mortality, andneonatal hypoglycaemia). This was due to design limitations in the included trials, small sample sizes in the trials contributing data, wide CIs crossing both the line of no effect and the line of appreciable benefit and/or harm, and often few events. We are therefore uncertain whether CSII or MDI improves outcomes for pregnant women with diabetes and their infants, and the results of further studies may differ substantially from those presented in this review.

AUTHORS' CONCLUSIONS

There is no evidence to support the use of one particular form of insulin administration over another for pregnant women with diabetes. There are only a small number of trials appropriate for meta-analysis, a small number of women included and questionable generalisability of the trial population.Pump technology has progressed since these trials were undertaken. Well-designed randomised trials are required to evaluate comparisons such as patch pumps against MDI and more conventional CSII against MDI. These trials should be adequately powered to assess the effect of interventions, and report the core set of outcomes used in Cochrane reviews of diabetes in pregnancy. Trials to assess the effects of pumps on birthweight and macrosomia rates are needed. It would be beneficial for future trials to undertake longer-term follow-up of participants and their infants, assess women's preferences, and conduct an economic evaluation.

Novel metabolic biomarkers of cardiovascular disease

Coronary heart disease (CHD) accounts for one in every six deaths in US individuals. Great advances have been made in identifying important risk factors for CHD, such as hypertension, diabetes mellitus, smoking and hypercholesterolaemia, which have led to major developments in therapy. In particular, statins represent one of the greatest successes in the prevention of CHD. While these standard risk factors are important, an obvious opportunity exists to take advantage of ongoing scientific research to better risk-stratify individuals and to identify new treatment targets. In this Review, we summarize ongoing scientific research in a number of metabolic molecules or features, including lipoproteins, homocysteine, calcium metabolism and glycaemic markers. We evaluate the current state of the research and the strength of evidence supporting each emerging biomarker. We also discuss whether the associations with CHD are strong and consistent enough to improve current risk stratification metrics, and whether these markers enhance our understanding of the underlying biology of CHD and thus point towards new treatment options.

Hemoglobin A(1c) in nondiabetic patients: an independent predictor of coronary artery disease and its severity

OBJECTIVE

To examine the association between hemoglobin A(1c) (HbA(1c)) and the presence, severity, and complexity of angiographically proven coronary artery disease (CAD) in nondiabetic patients.

PATIENTS AND METHODS

We performed a single-center, observational, cross-sectional study of 1141 consecutive nondiabetic patients who underwent coronary angiography from January 1, 2011, through December 31, 2011. The study population was divided into 4 interquartiles according to HbA(1c) levels (<5.5%, 5.5%-5.7%, 5.8%-6.1%, and >6.1%).

RESULTS

Patients with higher HbA(1c) levels tended to be older, overweight, and hypertensive, had higher blood glucose levels, and had lower glomerular filtration rates. Higher HbA(1c) levels were associated in a graded fashion with the presence of CAD, disease severity (higher number of diseased vessels and presence of left main and/or triple vessel disease), and disease complexity (higher SYNTAX score, higher number of patients in intermediate or high SYNTAX tertiles, coronary calcium, and chronic total occlusions). After adjustment for major conventional cardiovascular risk factors, compared with patients with HbA(1c) levels less than 5.5%, the odds ratios of occurrence of CAD in the HbA(1c) quartiles of 5.5% to 5.7%, 5.8% to 6.1%, and greater than 6.1% were 1.8 (95% CI, 1.2-2.7), 3.5 (95% CI, 2.3-5.3), and 4.9 (95% CI, 3.0-8.1), respectively.

CONCLUSION

The HbA(1c) level has a linear incremental association with CAD in nondiabetic individuals. The HbA(1c) level is also independently correlated with disease severity and higher SYNTAX scores. Thus, HbA(1c) measurement could be used to improve cardiovascular risk assessment in nondiabetic individuals.

The incidence of type 2 diabetes in the United Kingdom from 1991 to 2010

AIMS

To characterize the incidence of type 2 diabetes in the UK over the previous 20 years; and determine if there has been an increase in people aged 40 years or less at diagnosis.

METHODS

For this retrospective cohort study, patients newly diagnosed with type 2 diabetes between 1991 and 2010 were identified from the UK Clinical Practice Research Datalink (CPRD). Patient data were grouped into 5-year intervals by year of diagnosis and age at diagnosis. A standardized incidence ratio (SIR) was determined (1991-1995 = 100). The percentage of newly diagnosed patients for each age group and aged ≤40 years was calculated for each 5-year calendar period. The incidence rate by age and 5-year calendar period was also determined.

RESULTS

In 2010, the crude incidence rate of type 2 diabetes was 515 per 100,000 population. The overall SIR increased to 158 (95% CI 157-160, p < 0.001), 237 (235-238, p < 0.001) and 275 (273-276, p < 0.001) for 1996-2000, 2001-2005 and 2006-2010, respectively. For those ≤40, the respective values were 217 (209-226, p < 0.001), 327 (320-335, p < 0.001) and 598 (589-608, p < 0.001). An increase in incidence occurred with increasing 5-year calendar period. The incidence of type 2 diabetes was higher for males after the age of 40 and higher for females aged ≤40. The percentage of patients aged ≤40 years at diagnosis increased with each increasing 5-year calendar period (5.9, 8.4, 8.5 and 12.4%, respectively).

CONCLUSIONS

There was a significant increase in the incidence of diagnosed type 2 diabetes between 1991 and 2010 and the proportion of people diagnosed at a relatively early age has increased markedly.

Association of glycated hemoglobin with carotid intimal medial thickness in Asian Indians with normal glucose tolerance

AIM

To assess the association of glycated hemoglobin (HbA1c) levels with carotid intimal medial thickness (CIMT) in Asian Indians with normal glucose tolerance (NGT).

METHODS

Subjects with NGT were recruited from the Chennai Urban Rural Epidemiology Study carried out on a representative population of Chennai, South India. All subjects had fasting plasma glucose <100 mg/dl (5.6 mmol/l) and 2-h post load plasma glucose <140 mg/dl (7.8 mmol/l). HbA1c was measured using the Biorad Variant machine. CIMT was measured on the right common carotid artery using high-resolution B-mode ultrasonography.

RESULTS

The study group included 1383 NGT subjects, of whom 760 (54.9%) were women. The mean CIMT value in the 1st quartile of HbA1c (<5.2%) was 0.65 and it increased significantly to 0.73 in the last quartile of HbA1c (>5.8) (p<0.001). Regression analysis showed that HbA1c had a strong association with CIMT after adjusting for age, gender, waist circumference, systolic and diastolic blood pressure, LDL cholesterol, serum triglycerides, HOMA-IR and smoking (ß - 0.046, p=0.047).

CONCLUSION

Even among subjects with NGT, there is a significant increase in CIMT with increasing levels of HbA1c, showing the value of using HbA1c for diagnosis of glucose intolerance.

Influence of iron metabolism indices on HbA1c in non-diabetic pregnant women with and without iron-deficiency anemia: effect of iron supplementation

AIMS

Condition that influence erythrocyte turnover also affect HbA1c. Although many forms of anemia are associated with lowering of HbA1c, iron-deficiency anemia (IDA) tends to increase HbA1c. In this study, we examined the relationship between HbA1c and erythrocyte indices in non-diabetic pregnancy and assessed the effect of iron supplementation on HbA1c.

MATERIALS AND METHODS

150 women were studied (30 non-diabetic), non-pregnant, non-anemic women in child bearing women with varying parity as controls (Gp 1); 30 non-diabetic, non-anemic pregnant women in first trimester of pregnancy (Gp 2a); 30 non-diabetic, non-anemic pregnant women in second trimester of pregnancy (Gp 2b); 30 non-diabetic, non-anemic pregnant women in third trimester of pregnancy (Gp 2c) and 30 non-diabetic pregnant women with IDA (Gp 2d). HbA1c, OGTT, erythrocyte indices and iron metabolic indices were determined in Gp 2d subjects not supplemented with iron and repeated these indices after 3 months of iron-supplementation.

RESULTS

The mean fasting and postprandial blood glucose levels (79.9±8.0mg/dl, 108.1±14.1mg/dl) in Gp 1 were found to be significantly lower in first trimester among Gp 2a (74.4±5.3mg/dl and 97.2±11.1mg/dl), in second trimester among Gp 2b (76.2±5.2mg/dl and 103.4±7.9mg/dl) followed by increase in IIIrd trimester among Gp 2c (82.3±5.7mg/dl and 112.5±8.5mg/dl) subjects. A significant difference in HbA1c was also observed among the groups (HbA1c 4.7±0.3% in Gp 1; 4.6±0.4% in Gp 2a; 4.5±0.3 in Gp 2b; 4.7±0.3 in Gp 2c). Among Gp 2d subjects, HbA1c was 5.2±0.3% and the level decreased after iron supplementation to 5.1±0.3%. Significant correlation between erythrocyte indices, iron metabolic indices and HbA1c was also observed.

CONCLUSION

We conclude that consideration should be given for performing glucose testing in patients with IDA to ascertain the reliability of HbA1c in the diagnosis of diabetes. HbA1c concentrations in diabetic patients with IDA should be interpreted with caution.

HbA1c in pregnancy

During pregnancy, the glucose levels vary according to the hormonal changes and the metabolic needs necessary to maintain fetal nutrition but strict glycemic control is essential to minimize the maternal and fetal morbidity and mortality of pregnancies complicated by diabetes. Although considered the "gold standard" for diagnosis, measurement of glucose in the blood is subject to several limitations, many of which are not widely appreciated. Measurement of A1c for diagnosis is appealing as with one number, a total, integrated view of glycemia over time is derived though it has some inherent limitations. Thus, supplementation with HbA1c, as is common outside pregnancy, seems appropriate. Before pregnancy, the target for metabolic control in women with diabetes is HbA1c values near the normal range. However, the upper normal range of HbA1c during normal pregnancy is only sparsely investigated with different methods though recently a number of papers have been published regarding the determination of reference ranges for HbA1c in pregnancy. These changes may have clinical implications for the assessment and management of glycemic control in diabetic pregnancy and calls for establishment of separate reference limits of HbA1c levels in different trimesters as compared to general population.

Impact of a pay-for-performance incentive scheme on age, sex, and socioeconomic disparities in diabetes management in UK primary care

We examined the impact of a major pay-for-performance initiative introduced into UK primary care in 2004 on disparities in diabetes management between age, sex, and socioeconomic groups in this retrospective cohort study. We used data from the General Practice Research Database enrolling 422 family practices. Existing disparities in risk factor management (HbA1c, blood pressure, cholesterol) narrowed between men and women. Younger patients (<45 years) with diabetes appear to have benefited less from Quality and Outcomes Framework than older patients, resulting in some widening of existing age group disparities. Patients living in affluent and deprived areas appeared to have derived a similar level of benefit from pay for performance.

Childhood cognition and risk factors for cardiovascular disease in midadulthood: the 1958 British Birth Cohort Study

OBJECTIVES

We sought to establish whether associations between childhood cognition and risk factors for cardiovascular disease in adulthood are explained by common causes, or adult social position or health behavior.

METHODS

We analyzed associations between cognition at age 11 and cardiovascular disease risk factors at age 45 in the 1958 British birth cohort (n=9377), with and without adjustment for covariates.

RESULTS

General ability was inversely associated with systolic and diastolic blood pressure, glycosylated hemoglobin, triglycerides (in women), body mass index, and waist circumference. Systolic blood pressure decreased by 0.47 mm Hg (95% confidence interval [CI]=-0.90, -0.05) for a 1-standard-deviation increase in ability. Separate adjustment for social class at birth, education level by adulthood, adult social class, and health behaviors reduced the associations respectively by 14% to 34%, 36% to 50%, 14% to 36%, and 24% to 73%. Full adjustment reduced associations between ability and risk factors at age 45 years by 43% to 92%, abolishing all associations.

CONCLUSIONS

Increments across the distribution of childhood cognition are associated with improvements in cardiovascular risk profile in midlife, with associations primarily mediated through adult health behavior and social destinations.

Glycosylated hemoglobin and the risk of death and cardiovascular mortality in the elderly

BACKGROUND AND AIMS

Glycosylated hemoglobin (HbA(1c)) has been associated with incident cardiovascular disease (CVD), but the findings are inconsistent. We tested the hypothesis that HbA(1c) may be associated with an increased risk of death and cardiovascular mortality in older adults.

METHODS AND RESULTS

We evaluated the association between HbA(1c) with all-cause and cardiovascular mortality in 810 participants without a history of diabetes in a sub-study of the Cardiovascular Health Study (CHS), a community cohort study of individuals > or =65 years of age. Glycosylated hemoglobin was measured at baseline and all-cause and cardiovascular mortality was assessed during the follow-up period. The relation between baseline HbA(1c) and death was evaluated with multivariate Cox proportional hazards regression models. After a median follow-up of 14.2 years, 416 deaths were observed. The crude incidence rates of all-cause mortality across HbA(1c) groups were: 4.4% per year, 4.3% per year and 4.6% per year for tertile 1 (< or =5.6%), tertile 2 (5.61-6.20%) and tertile 3 (> or =6.21%), respectively. In unadjusted and fully adjusted analyses, baseline HbA(1c) was not associated with all-cause mortality and cardiovascular mortality (hazard ratio: 1.16 [95% confidence interval 0.91-1.47] and hazard ratio: 1.31 [95% confidence interval 0.90-1.93], respectively for the highest HbA(1c) tertile compared with the lowest).

CONCLUSION

These results suggest that HbA(1c) does not significantly predict all-cause and cardiovascular mortality in non-diabetic community-dwelling older adults.

Haemoglobin A1c as a predictor of postoperative hyperglycaemia and complications after major colorectal surgery

Background

Hyperglycaemia following major surgery increases morbidity, but may be improved by use of enhanced-recovery protocols. It is not known whether preoperative haemoglobin (Hb) A1c could predict hyperglycaemia and/or adverse outcome after colorectal surgery.

Methods

Some 120 patients without known diabetes underwent major colorectal surgery within an enhanced-recovery protocol. HbA1c was measured at admission and 4 weeks after surgery. All patients received an oral diet beginning 4 h after operation. Plasma glucose was monitored five times daily. Patients were stratified according to preoperative levels of HbA1c (within normal range of 4·5–6·0 per cent, or higher).

Results

Thirty-one patients (25·8 per cent) had a preoperative HbA1c level over 6·0 per cent. These had higher mean(s.d.) postoperative glucose (9·3(1·5) versus 8·0(1·5) mmol/l; P &lt; 0·001) and C-reactive protein (137(65) versus 101(52) mg/l; P = 0·008) levels than patients with a normal HbA1c level. Postoperative complications were more common in patients with a high HbA1c level (odds ratio 2·9 (95 per cent confidence interval 1·1 to 7·9)).

Conclusion

Postoperative hyperglycaemia is common among patients with no history of diabetes, even within an enhanced-recovery protocol. Preoperative measurement of HbA1c may identify patients at higher risk of poor glycaemic control and postoperative complications.

Proficiency Testing of Hb A1c: A 4-Year Experience in Taiwan and the Asian Pacific Region

Background: The correlation between hemoglobin A1c (Hb A1c) and risk for complications in diabetic patients heightens the need to measure Hb A1c with accuracy. We evaluated the current performance for measuring Hb A1c in the Asian and Pacific region by examining data submitted by laboratories participating in the Taiwan proficiency-testing program.

Methods: Five fresh-pooled blood samples were sent to participating laboratories twice each year. The results were evaluated against target values assigned by the National Glycohemoglobin Standardization Program network laboratories; a passing criterion of ±7% of the target value was used. Measurement uncertainty at Hb A1c concentrations of 7.0% and 8.0% were determined.

Results: A total of 276 laboratories from 11 countries took part in the Hb A1c survey. At the Hb A1c concentrations tested method-specific interlaboratory imprecision (CVs) were 1.1%–13.9% in 2005, 1.3%–10.1% in 2006, 1.2%–8.2% in 2007, and 1.1%–6.1% in 2008. Differences between target values and median values from the commonly used methods ranged from −0.24% to 0.22% Hb A1c in 2008. In 2005 83% of laboratories passed the survey, and in 2008 93% passed. At 7.0% Hb A1c, measurement uncertainty was on average 0.49% Hb A1c.

Conclusions: The use of accuracy-based proficiency testing with stringent quality criteria has improved the performance of Hb A1c testing in the Asian and Pacific laboratories during the 4 years of assessment.

Management of gestational diabetes mellitus

The incidence of gestational diabetes mellitus (GDM) is on the increase and, if not diagnosed, managed and treated adequately, can have unfavorable maternal and fetal outcomes. Several studies have shown that glycemic values considered as adequate in the past when monitoring GDM failed to contain these adverse outcomes and randomized trials are needed to ascertain whether these targets should be lowered. Dietary restrictions remain the mainstay of GDM management and suitable physical exercise can help too. The use of rapid-acting insulin analogues (lispro and aspart) are novel treatments for improving metabolic control by reducing postprandial glycemia, while long-acting insulin analogues need to be evaluated by further studies for safety in clinical use before they can be prescribed. Numerous studies have found glyburide and metformin safe in women with GDM but more randomized controlled trials are needed, with a long-term follow-up of mother and child, to confirm these results.

Increased LDL cholesterol and CRP in infants of mothers with type 1 diabetes

BACKGROUND

Proatherogenic stimuli during foetal life may predispose to development of atherosclerosis in adulthood. Elevated plasma low-density lipoprotein (LDL) cholesterol and C-reactive protein (CRP) expression is associated with increased risk of atherosclerosis.

METHODS AND RESULTS

In this study, we examined how maternal type 1 diabetes affects foetal plasma LDL cholesterol and CRP. In comparison with healthy mothers, the plasma LDL cholesterol was not increased in the mothers with diabetes, however, the umbilical-cord plasma LDL cholesterol was increased in their infants. CRP was increased in infants of mothers with diabetes and high haemoglobin A1c (HbA1c, > or = 6.2%). Human placenta expresses microsomal triglyceride transfer protein (MTP), which facilitates secretion of apolipoprotein B-containing lipoproteins. Microsomal triglyceride transfer activity was slightly higher (11%) in placentas from mothers with diabetes and HbA1c > or = 6.2% compared with the controls.

CONCLUSION

The results suggest that maternal type 1 diabetes increases the foetal plasma LDL cholesterol and CRP concentration and thus might predispose the offspring to development of atherosclerosis.

Diabetes control in a primary care setting: a retrospective study of 651 patients

BACKGROUND AND OBJECTIVES

As part of an ongoing evaluation of the process of care, the management of type 2 diabetes in primary healthcare settings was studied in a series of audits with the objective of improving diabetes care in a primary care center of the Saudi National Guard Health Affairs, Riyadh, Saudi Arabia.

METHODS

A sample of 30 files was randomly selected every 2 weeks from a sampling frame of medical records of type 2 diabetes patients seen over the previous two weeks. The criterion of good management was arbitrarily defined as a glycated hemoglobin (HbA(1c)) less than 7%, with a test frequency of once every 3 months. The proportion of patients not conforming to the criterion was reported back to the care providers. Specially trained nurses did all randomization, data extraction, and entry.

RESULTS

Data were extracted form 651 medical records, including 355 (54.5%) for females and 296 (45.5%) for males. Both the mean and median age of those studied was 53 years. Mean HbA(1c) was 9.0+/-2.0%, mean fasting plasma glucose was 9.9A+/-3.9 mmol/L, and mean 2-hour postprandial plasma glucose was 15.0+/-5.3 mmol/L. In 20.6% (134/651) (95% CI, 17.5%-23.9%) of patients the HbA(1c) level was less than 7%. Only 10.4% (68/651) (95% CI, 8.2%-13.0%) had HbA(1c) measured in the previous 3 months that was less than 7.0% and thus met the criterion for good management. In the previous 3 months, 55.4% (95% CI, 51.5%-59.3%) had been tested for HbA(1c).

CONCLUSION

Management of diabetes at the primary care level leaves much to be desired. There is a need for an ongoing process of evaluation to follow up the implementation of care guidelines.

Initiation of insulin glargine therapy in type 2 diabetes subjects suboptimally controlled on oral antidiabetic agents: results from the AT.LANTUS trial

OBJECTIVE

For many patients with type 2 diabetes, oral antidiabetic agents (OADs) do not provide optimal glycaemic control, necessitating insulin therapy. Fear of hypoglycaemia is a major barrier to initiating insulin therapy. The AT.LANTUS study investigated optimal methods to initiate and maintain insulin glargine (LANTUS, glargine, Sanofi-aventis, Paris, France) therapy using two treatment algorithms. This subgroup analysis investigated the initiation of once-daily glargine therapy in patients suboptimally controlled on multiple OADs.

RESEARCH DESIGN AND METHODS

This study was a 24-week, multinational (59 countries), multicenter (611), randomized study. Algorithm 1 was a clinic-driven titration and algorithm 2 was a patient-driven titration. Titration was based on target fasting blood glucose < or =100 mg/dl (< or =5.5 mmol/l). Algorithms were compared for incidence of severe hypoglycaemia [requiring assistance and blood glucose <50 mg/dl (<2.8 mmol/l)] and baseline to end-point change in haemoglobin A(1c) (HbA(1c)).

RESULTS

Of the 4961 patients enrolled in the study, 865 were included in this subgroup analysis: 340 received glargine plus 1 OAD and 525 received glargine plus >1 OAD. Incidence of severe hypoglycaemia was <1%. HbA(1c) decreased significantly between baseline and end-point for patients receiving glargine plus 1 OAD (-1.4%, p < 0.001; algorithm 1 -1.3% vs. algorithm 2 -1.5%; p = 0.03) and glargine plus >1 OAD (-1.7%, p < 0.001; algorithm 1 -1.5% vs. algorithm 2 -1.8%; p = 0.001).

CONCLUSIONS

This study shows that initiation of once-daily glargine with OADs results in significant reduction of HbA(1c) with a low risk of hypoglycaemia. The greater reduction in HbA(1c) was seen in patients randomized to the patient-driven algorithm (algorithm 2) on 1 or >1 OAD.

Obesity and type 2 diabetes risk in midadult life: the role of childhood adversity

OBJECTIVE

Child abuse has been associated with poorer physical health in adulthood, but less is known about childhood adversity more broadly, including neglect and family problems, or the pathways from adversity to adult disease. We have examined how different stressful emotional or neglectful childhood adversities are related to adiposity and glucose control in midadulthood, taking into account childhood factors, and whether the relationships are mediated by adult health behaviors and socioeconomic position.

METHODS

This was a prospective longitudinal study of 9310 members of the 1958 British birth cohort who participated in a biomedical interview at 45 years of age. Primary outcomes consisted of continuous measures of BMI, waist circumference, and glycosylated hemoglobin at 45 years and categorical indicators: total obesity (BMI > or = 30), central obesity (waist circumference: > or = 102 cm for men and > or = 88 cm for women), and glycosylated hemoglobin level of > or = 6.

RESULTS

The risk of obesity increased by 20% to 50% for several adversities (physical abuse, verbal abuse, witnessed abuse, humiliation, neglect, strict upbringing, physical punishment, conflict or tension, low parental aspirations or interest in education, hardly takes outings with parents, and father hardly reads to child). Adversities with the strongest associations with adiposity (eg, physical abuse) tended to be associated with glycosylated hemoglobin levels of > or = 6, but in most cases associations were explained by adjustment for adulthood mediators such as adiposity. Effects of other adversities reflecting less severe emotional neglect and family environment were largely explained by childhood socioeconomic factors.

CONCLUSIONS

Some childhood adversities increase the risk of obesity in adulthood and thereby increase the risk for type 2 diabetes. Research is needed to understand the interrelatedness of adversities, the social context of their occurrence, and trajectories from adversity to adult disease.

Continuous subcutaneous insulin infusion versus multiple daily injections of insulin for pregnant women with diabetes

BACKGROUND

Diabetes causes a rise in blood glucose above normal physiological levels causing damage to many systems including the cardiovascular and renal systems. Pregnancy causes a physiological reduction in insulin action; for those women who have pre-gestational diabetes, this results in an increasing insulin requirement. There are several methods of administering insulin. Conventionally, insulin has been administered subcutaneously, formally referred to as intensive conventional treatment, but now more usually referred to as multiple daily injections (MDI). An alternative insulin administration method is the continuous subcutaneous insulin infusion pump (CSII).

OBJECTIVES

To compare continuous subcutaneous insulin infusion with MDI of insulin for pregnant women with diabetes.

SEARCH STRATEGY

We searched the Cochrane Pregnancy and Childbirth Group's Trials Register (November 2006).

SELECTION CRITERIA

Randomised controlled trials comparing CSII with MDI for pregnant women with diabetes.

DATA COLLECTION AND ANALYSIS

Three authors independently assessed studies and extracted data.

MAIN RESULTS

Two studies (60 women with 61 pregnancies) were included. There was a significant increase in mean birthweight associated with CSII as opposed to MDI (weighted mean difference 220.56, 95% confidence interval (CI) -2.09 to 443.20; two trials, 61 participants). However, taking into consideration the lack of significant difference in rate of macrosomia (birthweight greater than 4000 g) (relative risk (RR) 3.20, 95% CI 0.14 to 72.62; two trials, 61 participants), this is not viewed by the authors as clinically significant. No significant differences were found in any other outcomes measured, which may reflect the small number of trials suitable for meta-analysis and the small number of participants in the included studies. No significant differences were found in perinatal mortality (RR 2.00, 95% CI 0.20 to 19.91), fetal anomaly (RR 1.07, 95% CI 0.07 to 15.54), maternal hypoglycaemia (RR 3.00, 95% CI 0.35 to 25.87) or maternal hyperglycaemia (RR 7.00, 95% CI 0.39 to 125.44).

AUTHORS' CONCLUSIONS

There is a dearth of robust evidence to support the use of one particular form of insulin administration over another for pregnant women with diabetes. The data are limited because of the small number of trials appropriate for meta-analysis, small study sample size and questionable generalisability of the trial population. Conclusions cannot be made from the data available and therefore a robust randomised trial is needed. The trial should be adequately powered to assess the efficacy of continuous subcutaneous insulin infusion versus multiple daily injections in terms of appropriate outcomes for women with diabetes.

Prenatal exposures and glucose metabolism in adulthood: are effects mediated through birth weight and adiposity?

OBJECTIVE

Birth weight has been associated with the risk of type 2 diabetes in several studies. We investigated whether prenatal influences on birth weight (gestational age, parity, preeclampsia, prepregnancy BMI, smoking during pregnancy, and socioeconomic position [SEP]) were associated with glucose metabolism in midlife and the role of birth weight for gestational age (BGA) and adult adiposity in mediating these associations.

RESEARCH DESIGN AND METHODS

Data from 7,518 participants of the 1958 British Birth Cohort with information on A1C at age 45 years were analyzed. Associations between prenatal exposures and A1C > or =6% were examined using a series of logistic regression models. The basic model consisted of all prenatal factors (except parity) adjusted for sex and family history of type 2 diabetes. Further adjustments included BGA only, concurrent adiposity only (BMI and waist circumference), and BGA plus adiposity.

RESULTS

In the basic model, preeclampsia (odds ratio 1.78 [95% CI 1.14-2.80]), prepregnancy BMI > or =25 kg/m(2) (1.90 [1.45-2.47]), maternal smoking (1.33 [1.04-1.71]), and manual SEP (1.87 [1.36-2.58]) were independently associated with A1C at 45 years of age. Adjustment for BGA had little impact on the prenatal factors/A1C associations, whereas adjustment for adult adiposity at 45 years substantially reduced associations for prepregnancy BMI, smoking during pregnancy, and SEP.

CONCLUSIONS

Prenatal exposures were related to blood glucose levels in mid-adulthood. Associations for several prenatal factors were largely mediated through adult adiposity but surprisingly not through birth weight. Prenatal exposures are likely to have the strongest effect on glucose metabolism indirectly through their influence on adiposity.

Diabetes risk in British adults in mid life: a national prevalence study of glycated haemoglobin

AIMS

Information on the population at risk of developing Type 2 diabetes in the UK is scarce. We used data from the 1958 British birth cohort to estimate geographical and socio-economic variations in HbA(1c) in mid life.

METHODS

Participants (n = 7799) born in England, Scotland and Wales and currently living in the UK. Individuals were classified according to the presence of Type 2 diabetes and by thresholds of HbA(1c). HbA(1c)> or = 5.5 was used as an indicator for possible subclinical alterations in glucose metabolism.

RESULTS

The majority of the population had HbA(1c) < 5.5% (79.3%); 16.7% had HbA(1c) 5.5-5.9%, 2.0% 6.0-6.9% and 0.6% had HbA(1c)> or = 7.0%. Individuals from manual socio-economic groups and those living in the East of England and Scotland had a higher prevalence of HbA(1c) at or above the upper normal range (5.5%).

CONCLUSIONS

Estimates from this nationwide sample suggest that a proportion of Britons are likely to have subclinical alterations in glucose metabolism by their mid 40s, and this proportion is greater in some socio-economic groups and geographical regions than in others.

Glycated hemoglobin as a marker of cardiovascular risk

PURPOSE OF REVIEW

Diabetes mellitus is an established risk factor for cardiovascular disease. This review examines glycated hemoglobin, an indicator of long-term average blood glucose concentrations, in risk prediction for cardiovascular disease.

RECENT FINDINGS

Glycated hemoglobin concentrations predict cardiovascular disease risk in people with diabetes, and trial data suggest that good blood glucose control is associated with reduction in cardiovascular disease. Elevated glycated hemoglobin levels below the thresholds accepted for diabetes are also associated with increasing cardiovascular disease risk independent of classical risk factors in a continuous relationship across the whole normal distribution. A 1% increase in absolute concentrations of glycated hemoglobin is associated with about 10-20% increase in cardiovascular disease risk. The continuous relationship is most evident for coronary heart disease in men; the shape of the risk curve is less clear for women and for other cardiovascular endpoints such as stroke or peripheral vascular disease.

SUMMARY

Glycated hemoglobin concentration predicts cardiovascular risk both in people with diabetes and in the general population, and may help identify individuals at higher risk of cardiovascular disease for targeted interventions, including blood pressure or cholesterol reduction. Understanding the nature of this relationship may inform new preventive and therapeutic interventions.

Placental triglyceride accumulation in maternal type 1 diabetes is associated with increased lipase gene expression

Maternal diabetes can cause fetal macrosomia and increased risk of obesity, diabetes, and cardiovascular disease in adulthood of the offspring. Although increased transplacental lipid transport could be involved, the impact of maternal type 1 diabetes on molecular mechanisms for lipid transport in placenta is largely unknown. To examine whether maternal type 1 diabetes affects placental lipid metabolism, we measured lipids and mRNA expression of lipase-encoding genes in placentas from women with type 1 diabetes (n = 27) and a control group (n = 21). The placental triglyceride (TG) concentration and mRNA expression of endothelial lipase (EL) and hormone-sensitive lipase (HSL) were increased in placentas from women with diabetes. The differences were more pronounced in women with diabetes and suboptimal metabolic control than in women with diabetes and good metabolic control. Placental mRNA expression of lipoprotein lipase and lysosomal lipase were similar in women with diabetes and the control group. Immunohistochemistry showed EL protein in syncytiotrophoblasts facing the maternal blood and endothelial cells facing the fetal blood in placentas from both normal women and women with diabetes. These results suggest that maternal type 1 diabetes is associated with TG accumulation and increased EL and HSL gene expression in placenta and that optimal metabolic control reduces these effects.

Vitamin D status and glucose homeostasis in the 1958 British birth cohort: the role of obesity

OBJECTIVE

Obesity is a well-known risk factor for vitamin D deficiency. We evaluated the interrelationship between vitamin D status, body size, and glucose homeostasis, measured by HbA1c (A1C).

RESEARCH DESIGN AND METHODS

Data are from the survey of the 45-year-old 1958 British birth cohort (2002-2004). Information on A1C, 25-hydroxyvitamin D [25(OH)D; an indicator of vitamin D status], and BMI was collected from 7,198 Caucasian subjects.

RESULTS

25(OH)D was < 75 nmol/l in 80% of the obese subjects (BMI > or = 30 kg/m2) versus 68% of the other subjects (P < 0.0001). Serum 25(OH)D decreased and A1C increased by increasing BMI (P < 0.0001 for both comparisons). There was a nonlinear association between 25(OH)D and A1C: a steep linear decrease in A1C by 25(OH)D until 65 nmol/l and only smaller decreases with further increases. There was evidence for effect modification by BMI in the association between 25(OH)D and A1C (P < 0.0001), and differences appeared stronger for participants with higher compared with lower BMIs. After adjustment for sex, season, geographical location, physical activity, and social class, percent change in A1C by 10-nmol/l increase in 25(OH)D was -0.21 (95% CI -0.31 to -0.11) for BMI < 25 kg/m2, -0.25 (-0.37 to -0.13) for BMI 25-29.9 kg/m2, -0.65 (-0.95 to -0.34) for BMI 30-34.9 kg/m2, and -1.37 (-2.09 to -0.64) for BMI > or = 35 kg/m2.

CONCLUSIONS

Body size was a strong determinant for 25(OH)D, with concentrations being suboptimal in most obese participants. Randomized controlled trials [using dosages sufficient to improve 25(OH)D also for the obese] are required to determine whether clinically relevant improvements in glucose metabolism can be obtained by vitamin D supplementation.

Reference intervals for hemoglobin A1c in pregnant women: data from an Italian multicenter study

BACKGROUND

The reference intervals for hemoglobin A1c (Hb A1c) in pregnant women without diabetes are not well defined, and few examples of reference intervals established by networks of different laboratories are available.

METHODS

Five Italian Diabetic Care Units were involved in the study. Data were collected from 445 pregnant women without diabetes, selected on the basis of glucose challenge test results, and from 384 nonpregnant control women. The Hb A1c measurements were performed with HPLC systems aligned to the Diabetes Control and Complications Trial. Plasma glucose measurements were also performed locally. Both Hb A1c and glucose measurements were harmonized by running appropriate external quality assessment schemes. The reference intervals were calculated in terms of nonparametric 2.5th to 97.5th percentiles with 0.90 confidence intervals.

RESULTS

The Hb A1c measurements were reproducible (CV = 2.0%) and accurate [mean (SE) difference from the target values, -0.10 (0.06)%]. Glucose measurements were also reproducible (mean CV = 3.2%) and accurate [difference from the target values, -0.01 (0.04) mmol/L]. To calculate common reference intervals, we merged the data collected in the different centers. The Hb A1c reference intervals were 4.0%-5.5% for pregnant nondiabetic women and 4.8%-6.2% for nonpregnant controls.

CONCLUSIONS

Healthy pregnant women have lower Hb A1c concentrations than nonpregnant women. The reference intervals for Hb A1c in pregnant women should therefore be lower than those currently in use.

Reduced prevalence of early preterm delivery in women with Type 1 diabetes and microalbuminuria--possible effect of early antihypertensive treatment during pregnancy

AIMS

In normotensive women with Type 1 diabetes and microalbuminuria we previously found preterm delivery (< 34 weeks) in 23% of the pregnancies. Antihypertensive treatment was initiated in late pregnancy when preeclampsia was diagnosed and diastolic blood pressure > 90 mmHg. From April 2000 our routine was changed and early antihypertensive treatment with methyldopa was initiated if antihypertensive treatment was given prior to pregnancy, if urinary albumin excretion (UAE) was > 2 g/24 h, or blood pressure > 140/90 mmHg. The present study describes the impact of this more aggressive antiypertensive treatment in the prevalence of preterm delivery.

METHODS

The old cohort (1995-1999) consisted of 26 and the new cohort (2000-2003) of 20 pregnant women with Type 1 diabetes and microalbuminuria. All were referred before gestational week 17.

RESULTS

The cohorts were comparable with regard to age, diabetes duration, prepregnancy body mass index, HbA1c, blood pressure 121 (13)/71 (8) vs. 121 (14)/73 (8) mmHg [mean (sd)] and early UAE 69 (16-278) vs. 74 (30-287) mg/24 h (geometric mean and range). Antihypertensive treatment was initiated in the old cohort at 29 (20-33) weeks, n = 9, and in the new at 13 (0-34) weeks, n = 10. The prevalence of preterm delivery before 34 weeks was reduced from 23% to zero (P = 0.02), preterm delivery before 37 weeks from 62% to 40% (P = 0.15) and preeclampsia from 42% to 20% (P = 0.11). Perinatal mortality occurred in 4% vs. 0%. Birth weight was 3124 (767) g vs. 3279 (663) g.

CONCLUSION

Introduction of early antihypertensive treatment with methyldopa in normotensive pregnant women with Type 1 diabetes and microalbuminuria resulted in a significant reduction in preterm delivery before gestational week 34.

External quality assessment of HbA(1c) for point of care testing

OBJECTIVES

To evaluate the long term total imprecision of HbA(1c) testing within the county of Uppsala in relation to the Swedish analytical goal of coefficient of variation (CV) < 3% for HbA(1c) and to study the cost of an external quality assurance program for point-of-care HbA(1c) The county uses Bayer DCA 2000 for point-of-care HbA(1c) testing currently having 23 of these instruments.

METHODS

Method imprecision was assessed by analysis of patient samples performed as split samples during a 3 year period (2002-2004) as part of the quality assurance program for point-of-care HbA(1c) testing. The samples were first analysed on a Bayer DCA 2000 and the samples were then sent to the centralised laboratory for reanalysis with an HPLC system (Variant II, Biorad). The testing was performed approximately 8 times per year with each instrument.

RESULTS

The median CV between the HPLC method and the point-of-care instruments for each unit was slightly higher than 3%.

CONCLUSION

The DCA 2000 systems have an acceptable imprecision and agreement with the central laboratory. The test results show acceptable agreements within the county regardless where the patient is tested. The cost of the external quality assurance program is calculated to be approximately SEK 1340 (Euro 150) per instrument.

Increased plasma pro-B-type natriuretic peptide in infants of women with type 1 diabetes

BACKGROUND

Up to 40% of newborn infants of women with type 1 diabetes have echocardiographic signs of cardiomyopathy. Increased plasma concentrations of B-type natriuretic peptide (BNP) and its precursor (proBNP) are markers of cardiac failure and hypoxia in adults. In this study, we investigated whether plasma concentrations of proBNP and/or BNP are increased in infants of women with type 1 diabetes.

METHODS

Plasma BNP and proBNP were measured with RIAs. The proBNP assay measures both intact proBNP and NH(2)-terminal fragments derived from this precursor, whereas the BNP assay measures only BNP-32 and not proBNP.

RESULTS

Infants of women with diabetes and hemoglobin A(1c) (Hb A(1c)) > or =6.2% before delivery had a higher median plasma proBNP concentration (31 pmol/L; interquartile range, 21-47 pmol/L; n = 16) than infants of healthy women [16 (9-32) pmol/L; n = 21; P = 0.01]. Infants of women with diabetes and Hb A(1c) <6.2% (n = 15) had intermediate values. The plasma BNP and proBNP concentrations were closely associated (r(2) = 0.80; P < 0.0001); within the group of infants of women with diabetes and Hb A(1c) > or =6.2%, both correlated with the degree of fetal stress during labor.

CONCLUSIONS

Maternal diabetes and suboptimal metabolic control may affect the fetal heart and predominantly stimulate proBNP secretion in conjunction with perinatal stress.

HbA1c: A comparison of NGSP with IFCC transformed values

BACKGROUND

An approved IFCC reference method for measuring HbA1c, with a firm and reproducible correlation with NGSP values, is now available. We established (i) the degree of agreement of HbA1c results between the NGSP-certified and the IFCC-calibrated (converted to NGSP values) immunochemical method and (ii) the difference in the classification of control of diabetes mellitus (DM) in individual patients between the methods.

METHODS

HbA1c was measured on the same hemolysate from each patient by both methods (n=92). Results were analyzed by the kappa statistic, linear regression, and McNemar's chi(2) test.

RESULTS

Both methods achieved acceptable analytical performance. The kappa statistic measure of agreement was 0.65 and r(2)=0.937. Overall, 21 (22.8%) patients were classified differently in the extent of diabetes control (good, acceptable, or poor), with a significant difference between the 2 methods (p<0.0005).

CONCLUSIONS

The IFCC converted to NGSP values were significantly different from the previously used NGSP-certified method. The differences between the 2 methods are of sufficient magnitude that HbA1c results from these methods are not interchangeable. The IFCC method being scientifically superior in concept and design should replace the NGSP method. New HbA1c targets for DM management need to be established for the IFCC method.

A matrix-assisted laser desorption/ionization mass spectrometry study of the non-enzymatic glycation products of human globins in diabetes

The molecular species present in globins from healthy and diabetic subjects with and without chronic complications have been analyzed by matrix-assisted laser desorption/ionization mass spectrometry. The technique demonstrated the presence of glycated and glyco-oxidated species of both alpha- and beta-globins. Their abundances show a good linear relationship with respect to HbA1c values and with the mean daily plasma glucose levels over the 6 weeks preceding the investigation. Interestingly, slightly different behaviour is observed in the data from patients with and without chronic complications; the plots of HbA1c vs. the abundance of glycated and glyco-oxidated species show different slopes and different intercepts with the y-axis. To investigate this aspect the mean abundances of glyco-oxidated species from healthy subjects and from diabetic patients with and without complications were calculated. Higher values were found for the two last sets of samples, but no significant difference was found between them. These data could indicate different individual proclivities to oxidation and/or different oxidation kinetics related to behavioural and environmental factors.

Two prospective studies found that elevated 2-hr glucose predicted male mortality independent of fasting glucose and HbA1c

OBJECTIVE

To quantify the relative contribution of elevated 2-hr glucose, fasting glucose (FPG), and HbA1c to all-cause mortality.

STUDY DESIGN AND SETTING

A joint analysis of two prospective studies with baseline glycemia measurements.

RESULTS

The multivariate adjusted hazard ratios (HRs) corresponding to a one standard deviation increase in HbA1c were 1.14 (95% CI 1.03-1.25), 1.08 (0.98-1.19) for FPG and 1.15 (1.05-1.27) for 2-hr glucose, respectively. Entering the 2-hr glucose to the model based on the FPG and HbA1c significantly improved the prediction of mortality, whereas neither FPG, nor HbA1c added significant information once 2-hr glucose was in the models. In subjects with FPG <7.0 mmol/L and HbA1c < or = 6.5%, the HR was 1.35 (1.03-1.78) in men with 2-hr glucose > or = 7.8 mmol/L compared with men with 2-hr glucose <7.8 mmol/L.

CONCLUSION

Elevated 2-hr glucose was a predictor of mortality independent of the levels of fasting glucose and HbA1c.

Glycated hemoglobin level is strongly related to the prevalence of carotid artery plaques with high echogenicity in nondiabetic individuals: the Tromsø study

BACKGROUND

High levels of HbA1c have been associated with increased mortality and an increased risk of atherosclerosis assessed as carotid intima-media thickness or plaque prevalence. In the present population-based study, we examined the association between HbA1c and plaque prevalence with emphasis on plaque echogenicity in subjects not diagnosed with diabetes.

METHODS AND RESULTS

HbA1c measurements and ultrasonography of the carotid artery were performed in 5960 subjects (3026 women, 2934 men) 25 to 84 years of age. Plaque morphology was categorized into 4 groups from low echogenicity (soft plaque) to strong echogenicity (hard plaque). HbA1c was categorized into 5 groups: <5.0%, 5.0% to 5.4%, 5.5% to 5.9%, 6.0% to 6.4% and >6.4%. Carotid plaque prevalence increased with increasing HbA1c level (P for linear trend=0.002). The OR for hard plaques versus no plaques was 5.8 in the highest HbA1c group (>6.4%) compared with subjects in the lowest group (<5.0%) after adjustment for several possible confounders. The risk of predominantly hard plaques was also significantly associated with HbA1c levels, although the ORs at each level were somewhat lower than for hard plaques. With respect to the risk of soft plaques versus no plaques, no statistically significant relationship with HbA1c levels was found.

CONCLUSIONS

Metabolic changes reflected by HbA1c levels may contribute to the development of hard carotid artery plaques, even at modestly elevated levels.

Diabetes control and complications: the role of glycated haemoglobin, 25 years on

The long-term complications of diabetes have major consequences for individual subjects and growing healthcare delivery and cost implications for society. Evidence for the benefits of good glycaemic control, as monitored by glycated haemoglobin measurements, has been developed in the 25 years since they were introduced to the point where HbA(1c) assays play central roles in patient management, clinical guidance and audit, and clinical trial design. In this review this evidence is examined and three classes of uncertainty identified that diminish confidence in the effectiveness of these roles for HbA(1c). 1 Analytical variability between different methods for HbA(1c) has restricted the application of clinical targets and this problem has recently been addressed by reference method standardization. There are two approaches to this which result in different HbA(1c) values and this discrepancy needs to be resolved. 2 Biological variability in HbA(1c) values between individuals also restricts its predictive role when applied to populations. The correlations between HbA(1c) measurements and various components of glycaemia (overall, fasting, postprandial) are still uncertain and differences in protein glycation and de-glycation are greater between subjects than often thought. The influence of variability in erythrocyte life span is an area where research is needed, especially in diabetic subjects. 3 Clinical variability is the most important and complex area of uncertainty. A predictive link between HbA(1c) and clinical outcomes is not as clear-cut as often stated. The correlation with the development of microvascular disease is well established in Type 1 diabetes, but in Type 2 subjects (90% of those with diabetes) the evidence that HbA(1c) monitoring is of value in predicting or preventing macrovascular disease is not strong, although it is the major cause of morbidity and early death in this group. It is recommended that, as a matter of urgency, these issues be examined, particularly within the context of self-care in diabetes.

Evaluation of HbA1C results in an external quality assessment scheme in South Africa

BACKGROUND

Measuring HbA1c blood levels allows us to assess average glycaemia in individuals during the preceding 6-8 weeks. There is a clear association between increasing risk of complications with higher HbA1c values and a significant risk reduction of the complications with lower HbA1c values.

METHODS

The performance of South African laboratories in an External Quality Assurance scheme for HbA1c is reported.

CONCLUSIONS

A number of laboratories and methods do not meet the required analytical standards. South African laboratories should adopt measures similar to other regional and national initiatives to significantly improve laboratory performance and bring about harmonization of HbA1c assays.

Diabetes services in the UK: third national survey confirms continuing deficiencies

AIMS

To determine the current level of diabetes services and to compare the results with previous national surveys.

METHODS

A questionnaire was mailed to all paediatricians in the UK identified as providing care for children with diabetes aged under 16 years. Information was sought on staffing, personnel, clinic size, facilities, and patterns of care. Responses were compared with results of two previous national surveys.

RESULTS

Replies were received from 244 consultant paediatricians caring for an estimated 17 192 children. A further 2234 children were identified as being cared for by other consultants who did not contribute to the survey. Of 244 consultants, 78% expressed a special interest in diabetes and 91% saw children in a designated diabetic clinic. In 93% of the clinics there was a specialist nurse (44% were not trained to care for children; 47% had nurse:patient ratio >1:100), 65% a paediatric dietitian, and in 25% some form of specialist psychology or counselling available. Glycated haemoglobin was measured routinely at clinics in 88%, retinopathy screening was performed in 87%, and microalbuminuria measured in 66%. Only 34% consultants used a computer database. There were significant differences between the services provided by paediatricians expressing a special interest in diabetes compared with "non-specialists", the latter describing less frequent clinic attendance of dietitians or psychologists, less usage of glycated haemoglobin measurements, and less screening for vascular complications. Non-specialist clinics met significantly fewer of the recommendations of good practice described by Diabetes UK.

CONCLUSIONS

The survey shows improvements in services provided for children with diabetes, but serious deficiencies remain. There is a shortage of diabetes specialist nurses trained to care for children and paediatric dietitians, and a major shortfall in the provision of psychology/counselling services. The services described confirm the need for more consultant paediatricians to receive specialist training and to develop expertise and experience in childhood diabetes.

Improving glycaemic control of insulin-treated diabetic patients--a structured audit of specialist nurse intervention

Insulin-treated diabetic patients with poor glycaemic control are frequently referred to diabetes specialist nurses, but little data exist as to the effectiveness of this practice. We therefore analysed the progress of 43 prospectively referred insulin-treated patients with glycosylated haemoglobin (HbA1c) levels > 7.5%. Diabetes nurse intervention involved re-education, dietary advice and insulin dose adjustment. Improvement in control was defined as a final HbA1c < 7.0% or a fall of HbA1c of > 1.0% at 6 months post-intervention. Almost two-thirds (63%) of patients achieved improvement status, with no increase in body weight or hypoglycaemic episodes. Disappointingly, however, the 'non-improver' group (37%) showed a mean deterioration in HbA1c. In conclusion, diabetes nurse intervention for poorly controlled insulin-treated diabetic patients is generally effective, but intervention may be best targeted to responsive patients. The factors which influence diabetic patients' 'responsiveness to change' require further investigation.

Considerations on blood glucose management in Type 2 diabetes mellitus

In recent years the benefits of more intensive management in preventing or delaying the development and progression of diabetic complications have been well documented. What is not as well documented is how to motivate the person with diabetes to manage the condition, how to set, assess and quantify glucose goals, and the glucose variables that should be routinely measured. This review discusses the importance of setting targets and communicating them in a way that the patient understands. When aiming for a glycaemia target, balance is required (1) between achieving reduction of complications and causing an increased degree of hypoglycaemia, and (2) between what is achievable and what degree of benefit is gained. Target values given in guidelines should be adapted by the clinician to take into account the patient's susceptibility to hypoglycaemia, stage and type of complications, age and life expectancy, co-morbidity, social environment, understanding of the steps required and level of commitment to the treatment. Several suggestions are given regarding possible improvements and amendments to existing guidelines for diabetes management in treating to glucose goal. For example, attention should be drawn to the need to individualize goals and to consider education, long-term support, patient needs and treatment outcome when formulating diabetes management plans. The relative properties of the different glucose variables-fasting plasma glucose (FPG), postprandial plasma glucose (PPG), glycated haemoglobin A(1c) (HbA(1c)), and glycated protein-in terms of their convenience of measurement, usefulness and relevance to the physician and patient are also evaluated. When prioritising the variables to be measured it is suggested that where feasible, HbA(1c) should be the standard measurement by which to gauge risk and treatment efficacy. Serial measurements should be made and, where possible, the use of blood glucose meters encouraged, in order to obtain a blood glucose profile for the patient.

Self-monitoring of glucose levels for people with type 2 diabetes

To determine the most effective way of monitoring glucose levels as an indicator of glycaemic control in people with type 2 diabetes in the community, we conducted a criteria-based review of randomized controlled trials and systematic reviews of randomized controlled trials that studied the efficacy of various glucose monitoring strategies. We searched the Cochrane Library, Medline, Embase, CINAHL and BNIPlus databases for relevant studies. The journals 'Diabetes', 'Diabetic Medicine', 'Diabetologica', 'Evidence-Based Medicine' and 'Evidence-Based Nursing' were hand searched. The outcome of interest was glycaemic control, as measured by glycated haemoglobin (HbA(1c)). A total of 642 titles were identified from the search; three studies answered the question criteria and only one study met all the quality criteria. The study that met the criteria was a systematic review of four trials measuring the efficacy of self-monitoring of glucose levels. The reduction in HbA(1c) in those who monitored glucose levels was estimated to be -0.25% (95% Cl -0.61 - +0.10). This result shows a small improvement, but it is not statistically significant. A meta-analysis was also performed on three studies (n=278) comparing HbA(1c) in subjects who performed blood glucose monitoring with those who performed urine monitoring. The reduction in HbA(1c) when monitoring blood glucose rather than urine glucose was -0.03% (95% Cl -0.52 - +0.47). This result is not statistically significant. The efficacy of blood and urine glucose monitoring testing, for people with type 2 diabetes, in improving glycaemic control as measured by HbA(1c) levels is still questionable. A rigorous randomized controlled trial is needed to establish these answers although there is no evidence of harm. Clinical protocols that make recommendations for glucose monitoring strategies for people with type 2 diabetes should acknowledge that the evidence is weak. There is no basis to recommend one method above another.