Tests of glycemia in diabetes

Analysis of the method for conversion between levels of HbA1c and glycated albumin by linear regression analysis using a measurement error model

AIM

To establish a method for conversion between HbA(1c) and glycated albumin (GA) using a measurement error model (MEM).

METHODS

Type 2 diabetic patients, without complications that might affect either HbA(1c) or GA, were enrolled in the study (n=154, age 68.4+/-9.9). HbA(1c), GA and postprandial plasma glucose (PPG) levels were measured simultaneously on >or=3 occasions.

RESULTS

PPG showed a significant correlation with HbA(1c) and GA (p<0.001 for both). Correlation between HbA(1c) and GA was very high (r=0.747, p<0.001). When the independent variable was assumed to be GA, common regression analysis yielded a regression line HbA(1c)=2.59+0.204GA. When the independent variable was changed to HbA(1c), the regression line became GA=2.26+2.74HbA(1c). The y-intercept of the first line was significantly positive, whereas that of the second was not. The regression line using MEM was HbA(1c)=1.73+0.245GA. The y-intercept was 1.73+/-0.38 (p<0.001) and the slope was 0.245+/-0.018 (p<0.001), showing that 1% increase in HbA(1c) level corresponds to 4% increase in GA level.

CONCLUSIONS

The relationship between HbA(1c) and GA was examined by regression analysis using MEM. HbA(1c) levels in Japan appear to have a positive shift of approximately 1.7%. Incremental ratio 4 of GA vs. HbA(1c) showed good consistency with values derived from in vitro data.

Prevention of diabetic ketoacidosis and self-monitoring of ketone bodies: an overview

OBJECTIVE

Diabetic ketoacidosis (DKA) is associated with significant morbidity and mortality. Self-monitoring of ketone bodies by diabetes patients can be done using blood or urine. We compared the two self-monitoring methods and summarized recent developments in the epidemiology and management of DKA.

METHODS

MEDLINE and EMBASE were searched for relevant publications addressing the epidemiology, management and prevention of DKA up to 2009. The current, relevant publications, along with the authors' clinical and professional experience, were used to synthesize this narrative review.

FINDINGS

Despite considerable advances in diabetes therapy, key epidemiological figures related to DKA remained nearly unchanged during the last decades at a global level. Prevention of DKA - especially in sick day management - relies on intensive self-monitoring of blood glucose and subsequent, appropriate therapy adjustments. Self-monitoring of ketone bodies during hyperglycemia can provide important, complementary information on the metabolic state. Both methods for self-monitoring of ketone bodies at home are clinically reliable and there is no published evidence favoring one method with respect to DKA prevention.

CONCLUSIONS

DKA is still a severe complication potentially arising during prolonged hyperglycemic episodes with possibly fatal consequences. Education of patients and their social environment to promote frequent testing - especially during sick days - and to lower their glucose levels, as well as to recognize the early symptoms of hyperglycemia and DKA is of paramount importance in preventing the development of severe DKA. Both methods for self-monitoring of ketone bodies are safe and clinically reliable.

Hyperglycemia increases risk of gastric cancer posed by Helicobacter pylori infection: a population-based cohort study

BACKGROUND & AIMS

Although diabetes mellitus and hyperglycemia are considered to be possible risk factors for various types of malignancy, the epidemiologic evidence concerning gastric cancer is scarce. The aim of this study was to evaluate the impact of hemoglobin A1c (HbA1c) levels on gastric cancer occurrence and their interaction with Helicobacter pylori infection.

METHODS

A total of 2603 Japanese subjects aged>or=40 years were stratified into 4 groups according to baseline HbA1c levels (<or=4.9%, 5.0%-5.9%, 6.0%-6.9%, and >or=7.0%) and followed up prospectively for 14 years.

RESULTS

During the follow-up, 97 subjects developed gastric cancer. The age- and sex-adjusted incidence of gastric cancer significantly increased in the 6.0%-6.9% (5.1 per 1000 person-years; P<.05) and >or=7.0% groups (5.5 per 1000 person-years; P<.05) compared with the 5.0%-5.9% group (2.5 per 1000 person-years), whereas it was slightly but not significantly high in the <or=4.9% group (3.6 per 1000 person-years). This association remained substantially unchanged even after adjusting for the confounding factors including Helicobacter pylori seropositivity, (multivariate-adjusted hazard ratio [HR], 2.13; 95% confidence interval [CI]: 1.30-3.47 for the 6.0%-6.9% group and HR, 2.69; 95% CI: 1.24-5.85 for the >or=7.0% group). Among subjects who had both high HbA1c levels (>or=6.0%) and Helicobacter pylori infection, the risk of gastric cancer was dramatically elevated (interaction term, P=.004).

CONCLUSIONS

Our findings suggest that casual hyperglycemia is a risk factor for gastric cancer and is a possible cofactor increasing the risk posed by Helicobacter pylori infection.

HbA1c: how do we measure it and what does it mean?

PURPOSE OF REVIEW

Description of recent developments in the standardization of HbA1c measurement and interpretation of HbA1c results.

RECENT FINDINGS

HbA1c is extensively used in the management of patients with diabetes. The two major schemes to standardize HbA1c produce values that differ substantially. A prospective, multinational study revealed a linear correlation between HbA1c and average blood glucose. Some, but not all, assay methods are able to accurately measure HbA1c in individuals with common hemoglobin variants.

SUMMARY

Progress in standardization of methods for HbA1c measurement has significantly reduced variation among different methods. The improved accuracy could allow HbA1c to be used for screening and diagnosis of diabetes. A consensus document recommends that HbA1c be reported in both NGSP (%) and IFCC (mmol/mol) units. HbA1c results can be translated into estimated average glucose (eAG), which could be reported in addition to HbA1c.

Comparison of glycaemic control in patients with Type 2 diabetes on basal insulin and fixed combination oral antidiabetic treatment: results of a pilot study

This randomised, open-label, two-way cross-over study compared the coefficient of variance (CV) of fasting and postprandial blood glucose (FBG and PPBG) with insulin glargine (glargine) versus neutral protamine Hagedorn (NPH) insulin treatment in patients with Type 2 diabetes (T2DM). Patients (N=20) on oral antidiabetic drugs (OADs) were treated with NPH (at bedtime) or glargine (at dinnertime) for 12 weeks of each cross-over treatment period; OADs were continued. The FBG CV was calculated from self-monitored BG values and PPBG using venous blood samples, or continuous glucose monitoring system (CGMS). Both insulins provided similar improvements in glycaemic control; however, PPBG was significantly lower after a standard meal test (performed at 13:00 h the day after insulin injection) with glargine versus NPH (p=0.02). Thirteen versus 15 patients experienced >or=1 episode of hypoglycaemia with glargine versus NPH. The results suggest that glargine plus OADs is more effective in reducing PPBG fluctuations during the day than NPH plus OADs.

Glycemic control and survival of diabetic hemodialysis patients--importance of lower hemoglobin A1C levels

AIMS

The significance of hemoglobin A1C (HbA1C) on the survival of diabetic hemodialysis patients still remains controversial. We investigated the impact of HbA1C on the survival.

METHODS

A total of 122 diabetic patients on maintenance hemodialysis (age, 59.9+/-11.9 years [mean+/-SD]; hemodialysis duration: 53+/-38 months) were surveyed (survey period: 46+/-19 months).

RESULTS

The cumulative survival of the poor glycemic control group (mean HbA1C of 3-month period > or =6.3%, n=62) was significantly lower than that of the good group (HbA1C<6.3%, n=60), as determined by Kaplan-Meier estimation (P=0.0084, log-rank test). Kaplan-Meier analysis also demonstrated that both cardiovascular and non-cardiovascular mortalities were higher in the poor group than in the good group (P=0.0545 and P=0.0453, respectively). In a multivariate Cox proportional hazard model, the mean HbA1C was a significant predictor of survival (OR 1.260 per 1.0%, 95% CI 1.020-0.579, P=0.0325).

CONCLUSIONS

Poor glycemic control is an independent predictor of poor prognosis in diabetic hemodialysis patients. HbA1C is a clinically useful parameter for identifying the risk for mortality, both for cardiovascular and non-cardiovascular mortality, and that careful management of glycemic control by use of HbA1C is important.

Review of hemoglobin A(1c) in the management of diabetes

Hemoglobin HbA(1c) (A(1c)) has been used clinically since the 1980s as a test of glycemic control in individuals with diabetes. The Diabetes Control and Complications Trial (DCCT) demonstrated that tight glycemic control, quantified by lower blood glucose and A(1c) levels, reduced the risk of the development of complications from diabetes. Subsequently, standardization of A(1c) measurement was introduced in different countries to ensure accuracy in A(1c) results. Recently, the International Federation of Clinical Chemists (IFCC) introduced a more precise measurement of A(1c) , which has gained international acceptance. However, if the IFCC A(1c) result is expressed as a percentage, it is lower than the current DCCT-aligned A(1c) result, which may lead to confusion and deterioration in diabetic control. Alternative methods of reporting have been proposed, including A(1c) -derived average glucose (ADAG), which derives an average glucose from the A(1c) result. Herein, we review A(1c) , the components involved in A(1c) formation, and the interindividual and assay variations that can lead to differences in A(1c) results, despite comparable glycemic control. We discuss the proposed introduction of ADAG as a surrogate for A(1c) reporting, review imprecisions that may result, and suggest alternative clinical approaches.

Disturbed eating behaviors in Taiwanese adolescents with type 1 diabetes mellitus: a comparative study

OBJECTIVES

This study aimed to (i) compare disturbed eating behaviors in adolescents with type 1 diabetes mellitus (T1D) with a matched group of adolescents in Taiwan and (ii) examine the relationships of disturbed eating behaviors to body mass index (BMI) and metabolic control among adolescents with T1D.

METHODS

A cross-sectional study was conducted in southern Taiwan. Seventy-one adolescents with T1D (aged 10-22 yr; 41 females and 29 males) were matched to a group of non-diabetic adolescents. Adolescents completed two self-reported measures of eating behavior, the Bulimic Investigatory Test, Edinburgh and the Eating Attitude Test-26. Metabolic control was assessed by glycosylated hemoglobin A1c levels.

RESULTS

Both adolescent females and males with T1D had more symptoms of bulimia and bulimic behaviors than their non-diabetic peers. There were no group differences in the proportion of subthreshold eating disorders. BMI and metabolic control were significant factors predicting disturbed eating behaviors.

CONCLUSIONS

Both adolescent females and males with T1D exhibited a higher level of disturbed eating behaviors than their non-diabetic adolescent counterparts. Preventive programs that address disturbed eating behaviors should be provided for adolescents with T1D, particularly for adolescents with a high BMI and poor metabolic control.

The effects of trust in physician on self-efficacy, adherence and diabetes outcomes

Trust in physicians has been associated with a range of patient behaviors. However, previous research has not focused on the mechanisms by which trust affects health outcomes and mostly has made use of self-rated health. This study tested a theoretical model of variables influencing the relations of trust to both objective and self-rated health. We hypothesized that patients who trust their physicians more were likely to have stronger self-efficacy and outcome expectations. We expected this, in turn, to be associated with better treatment adherence and objective health outcomes. In addition, we hypothesized that highly trusting patients would be more likely to report better health status through enhanced self-efficacy. Data for this research came from a sample of 480 adult patients with type 2 diabetes in Taiwan. Patients completed measures of trust, self-efficacy, outcome expectations, adherence, and the SF-12 health survey. Objective outcomes, including body mass index, glycosylated hemoglobin, blood lipid, and diabetes-related complications, were assessed by follow-up chart review. The structural equation analyses which were implemented by LISREL VIII resulted in a proper solution that exhibited adequate fit. All hypothesized paths were statistically significant and in the predicted directions. The mediation roles of self-efficacy and outcome expectations were further confirmed by the results of structural equation modeling and bootstrap analyses. In the multivariate regression, although the relations of patient trust to blood lipid and self-rated health were confirmed, the direct link of trust to glycosylated hemoglobin was only significant in the bivariate model. This study clarifies the association of trust with different types of health outcomes and provides the empirical evidence that trust in physicians is associated with both self-rated health and therapeutic response. However, a more longitudinal study design is necessary to precisely determine both the strength and causality of these relationships.

Emerging role of dipeptidyl peptidase-4 inhibitors in the management of type 2 diabetes

BACKGROUND

In type 2 diabetes mellitus (T2DM) there is a progressive loss of beta-cell function. One new approach yielding promising results is the use of the orally active dipeptidyl peptidase-4 (DPP-4) inhibitors. However, every new compound for T2DM has to prove long-term safety especially on cardiovascular outcomes.

OBJECTIVES

Systematic review and meta-analysis of the effects of sitagliptin and vildagliptin therapy on main efficacy parameters and safety. SELECTION CRITERIA, DATA COLLECTION, AND ANALYSIS: Randomized controlled clinical studies of at least 12 weeks' duration in T2DM.

RESULTS

DPP-4 inhibitors versus placebo showed glycosylated hemoglobin A1c (A1c) improvements of 0.7% versus placebo but not compared to monotherapy with other hypoglycemic agents (0.3% in favor of controls). The overall risk profile of DPP-4 inhibitors was low, however a 34% relative risk increase (95% confidence interval 10% to 64%, P = 0.004) was noted for all-cause infection associated with sitagliptin use. No data on immune function, health-related quality of life and diabetic complications could be extracted.

CONCLUSIONS

DPP-4 inhibitors have some theoretical advantages over existing therapies with oral antidiabetic compounds but should currently be restricted to individual patients. Long-term data on cardiovascular outcomes and safety are needed before widespread use of these new agents.

Standardized evaluation of nine instruments for self-monitoring of blood glucose

BACKGROUND

Instruments for self-monitoring of blood glucose (SMBG) should undergo a standardized evaluation including a user-test before being marketed. In this study the results from standardized evaluations of nine different SMBG instruments are presented, and the standardized evaluation is discussed.

METHODS

Approximately 80 diabetes patients using three lots of test strips participated in each evaluation. Half of the patients were educated in how to use the meter, and the evaluations were carried out by both medical laboratory technologists (MLTs) and patients. Questionnaires were used to assess the user manual and the user-friendliness of the instrument.

RESULTS

The imprecision obtained by the patients (coefficients of variation [CVs] of 3.2-8.1%) were generally higher compared to that by the MLT (CVs of 2.3-5.9%). Three of the nine instruments did not achieve the quality goal based on the recommendation in the International Organization for Standardization's ISO 15197 guideline in the hands of diabetes patients. The bias from the comparison method ranged from -10.4% to +3.2%. There were significant lot-to-lot variations and hematocrit effects for some of the instruments. Temperature difference between the instruments and the test strip caused deterioration of the quality in one instrument. The user-friendliness was in general acceptable.

CONCLUSIONS

The quality of instruments for SMBG seems to have improved during recent years, although there are still analytical problems. A standardized evaluation protocol is necessary and should be regularly revised taking into account the development of new technology and the needs of the patients.

A review of glycated albumin as an intermediate glycation index for controlling diabetes

INTRODUCTION

This article reviews glycated albumin (GA) as a potential intermediate-term glycation index to fill the gap between self-monitoring of blood glucose (SMBG) and hemoglobin A1c testing in diabetes management. The introduction gives an assessment of available short-, medium-, and long-term glycemic indicators. METHODOLOGIES AND UTILITY: Methods of GA measurement are summarized, and the variance of normal and diabetic GA values are discussed. Greatest uniformity in GA measurement is generally associated with immunoassay and the newer affinity chromatography methodologies utilized by reference laboratories. Utility of GA measurement includes its value as a marker for glycation, its substantial relationship to diabetes complications such as nephropathy and coronary artery disease, and as an unambiguous indicator of glycemic control in diabetes patients undergoing hemodialysis. Studies support the utility of GA in detecting short-term changes in glycemic control, and GA testing has been strongly recommended for gestational diabetes.

RESULTS AND DISCUSSION

The results of a survey with mailings to over 3500 diabetes care professionals primarily in the United States are outlined and analyzed (margin of error: +/-6.5%, 95% confidence). Respondents strongly supported the need for a test for intermediate glycemic control as well as the utility of a rapid GA test as a monthly glycemic indicator.

CONCLUSIONS

Such a test, as yet unavailable, could increase compliance and enhance empowerment among diabetes patients. It also has the potential to reduce the number of recommended SMBG tests, which may result in significant health care cost savings.

Prevalence of elevated hemoglobin A1c among patients admitted to the hospital without a diagnosis of diabetes

CONTEXT

One in four hospitalized patients has diagnosed diabetes. The prevalence of unrecognized, or undiagnosed, diabetes among hospitalized patients is not well established.

OBJECTIVE

Our objective was to determine the prevalence of unrecognized probable diabetes in this patient population determined by elevated hemoglobin A1c (HbA1c) level.

DESIGN

We conducted a prospective observational cohort trial with retrospective follow-up of patients with elevated HbA1c levels and no diagnosis of diabetes. HbA1c levels were obtained for all patients.

SETTING

The study was conducted at an acute care general hospital.

PATIENTS

Patients included 695 adult, nonobstetric patients admitted on 11 d in 2006.

MAIN OUTCOME MEASURES

Outcome measures included rate of unrecognized probable diabetes, defined as admission HbA1c of more than 6.1% and no diagnosis of diabetes or treatment with antidiabetic medications before or during their admission and rate of unrecognized diabetes 1 yr after discharge.

RESULTS

Eighteen percent of hospitalized patients had elevated HbA1c levels without a diagnosis of diabetes. Random glucose levels poorly predicted elevated HbA1c levels (area under receiver operating characteristic curve, 0.60). Neither diagnosed diabetes nor HbA1c level was associated with length of stay or costs (P>0.1 for all comparisons). Only 15% of patients with elevated HbA1c levels who continued to receive care within the system studied had diabetes diagnosed in the year after the index admission.

CONCLUSIONS

Nearly one in five adult patients admitted to a large general hospital had unrecognized probable diabetes, based on elevated HbA1c levels. Random glucose levels during the hospital stay were poorly predictive of this condition. Few hospitalized patients with elevated HbA1c levels were diagnosed within the year after admission.

No relationship between mean plasma glucose and glycated haemoglobin in patients with cystic fibrosis-related diabetes

AIM

Cystic fibrosis-related diabetes (CFRD) prevalence has increased dramatically with the improved life expectancy of patients with cystic fibrosis (CF). Glycated haemoglobin (HbA(1c)) is an important tool for monitoring blood glucose control but, unlike in type 1 and type 2 diabetes, a correlation between HbA(1c), fructosamine and mean plasma glucose has not been clearly established in CF. This study aimed to examine the relationship between mean plasma glucose and HbA(1c) or fructosamine in stable patients with CFRD.

METHODS

Fifteen type 1 diabetes and 13 CFRD patients (HbA(1c)<9.0%; no anaemia), matched for age and body mass index (BMI), provided 72 capillary blood glucose profiles taken 3days/month for three months. At the end of this time, HbA(1c) and fructosamine were measured. Mean plasma glucose was estimated using the Diabetes Control and Complications Trial (DCCT) conversion formula, and linear regressions carried out to establish its relationship with HbA(1c) and fructosamine.

RESULTS

In type 1 diabetes patients, mean plasma glucose correlated significantly with HbA(1c) (r=0.68; P=0.005). In CFRD patients, no correlation was found between mean plasma glucose and HbA(1c) (r=0.24; P=0.460). Also, no association was found between mean plasma glucose, representing the month before blood sampling, and fructosamine in either group.

CONCLUSION

Unlike in type 1 diabetes, HbA(1c) did not correlate with mean plasma glucose in CFRD subjects. Thus, having a normal HbA(1c) may not be sufficient to indicate a low risk of diabetes complications in CFRD. Further studies are required to explain such a discrepancy.

Association between parental history of type 2 diabetes and glycemic control in urban African Americans

OBJECTIVE

The purpose of this study was to examine the association between parental history of type 2 diabetes and glycemic control among diabetic urban African Americans.

RESEARCH DESIGN AND METHODS

Study participants included 359 African Americans with type 2 diabetes from Baltimore, Maryland, enrolled in Project Sugar 2. Participants underwent an interview-administrated questionnaire that asked about family history, sociodemographics, clinical characteristics, and knowledge and perception of adequate glycemic control. Regression analysis was used to determine the association between parental history of diabetes and glycemic control, as measured by A1C.

RESULTS

In the comparisons between participants with and without a parental history of diabetes, those with a positive parental history tended to be younger, have higher glucose levels, and have higher blood glucose levels before calling a doctor (all P < 0.05). After adjustments for age, sex, and BMI, there was a significant association (P = 0.02) between A1C and parental history with the mean A1C difference between those with a positive and a negative parental history being 0.58%. However, after adjustment for duration of diabetes, the association was no longer significant (P = 0.11). However, there was a tendency for individuals with two diabetic parents to have higher A1C (P = 0.011).

CONCLUSIONS

From these results, we conclude that among the urban African American participants who were aware of their parental history of diabetes, a positive parental history was associated with worse glycemic control, partly due to longer duration of diabetes. Parental history did not appear to be associated with better knowledge or perception of adequate glycemic control.

Evidence for interindividual heterogeneity in the glucose gradient across the human red blood cell membrane and its relationship to hemoglobin glycation

OBJECTIVE

To determine whether interindividual heterogeneity in the erythrocyte (red blood cell [RBC]) transmembrane glucose gradient might explain discordances between A1C and glycemic control based on measured fructosamine.

RESEARCH DESIGN AND METHODS

We modeled the relationship between plasma glucose and RBC glucose as the concentration distribution (C(i)-to-C(o) ratio) of a nonmetabolizable glucose analog (14)C-3-O-methyl glucose ((14)C-3OMG) inside (C(i)) and outside (C(o)) RBCs in vitro. We examined the relationship between that distribution and the degree of glycation of hemoglobin in comparison with glycation of serum proteins (fructosamine), the glycation gap. A1C, fructosamine, and in vitro determination of the (14)C-3OMG distribution in glucose-depleted RBCs were measured in 26 fasted subjects.

RESULTS

The C(i)-to-C(o) ratio 0.89 +/- 0.07 for 3-O-methyl-d-glucopyranose (3OMG) ranged widely (0.72-1.04, n = 26). In contrast, urea C(i)-to-C(o) (1.015 +/- 0.022 [range 0.98-1.07], P < 0.0001) did not. Concerning mechanism, in a representative subset of subjects, the C(i)-to-C(o) ratio was retained in RBC ghosts, was not dependent on ATP or external cations, and was reestablished after reversal of the glucose gradient. The 3OMG C(i)-to-C(o) ratio was not correlated with serum fructosamine, suggesting that it was independent of mean plasma glucose. However, C(i)-to-C(o) did correlate with A1C (R(2) = 0.19) and with the glycation gap (R(2) = 0.20), consistent with a model in which differences in internal glucose concentration at a given mean plasma glucose contribute to differences in A1C for given level of glycemic control.

CONCLUSIONS

The data demonstrate interindividual heterogeneity in glucose gradients across RBC membranes that may affect hemoglobin glycation and have implications for diabetes complications risk and risk assessment.

Haemoglobin A1c analysis in the management of patients with diabetes: from chaos to harmony: Table 1

Effective management of patients with diabetes mellitus requires accurate assessments of blood glucose control. The best characterised marker of long term glycaemic control is whole blood haemoglobin A1c (HbA1c). Published clinical trials have identified quantitative and direct relationships between the HbA1c concentration and risks of diabetic microvascular complications. However, in order to practice evidence-based medicine, assays used to measure patient samples should ideally produce values comparable to the assays used in these trials. Numerous assays using chromatographic and immunological detection methods are used around the world. This paper briefly reviews the scientific evolution of HbA1c and its analysis, discusses the reasons why HbA1c assay standardisation is a challenge, describes the approaches that have been adopted to harmonise HbA1c assays, and addresses the current initiatives to standardise HbA1c globally. These efforts have established HbA1c as an essential component in the management of patients with diabetes mellitus and are likely to lead to the use of HbA1c in the screening/diagnosis of diabetes.

Translating the A1C assay into estimated average glucose values

OBJECTIVE

The A1C assay, expressed as the percent of hemoglobin that is glycated, measures chronic glycemia and is widely used to judge the adequacy of diabetes treatment and adjust therapy. Day-to-day management is guided by self-monitoring of capillary glucose concentrations (milligrams per deciliter or millimoles per liter). We sought to define the mathematical relationship between A1C and average glucose (AG) levels and determine whether A1C could be expressed and reported as AG in the same units as used in self-monitoring.

RESEARCH DESIGN AND METHODS

A total of 507 subjects, including 268 patients with type 1 diabetes, 159 with type 2 diabetes, and 80 nondiabetic subjects from 10 international centers, was included in the analyses. A1C levels obtained at the end of 3 months and measured in a central laboratory were compared with the AG levels during the previous 3 months. AG was calculated by combining weighted results from at least 2 days of continuous glucose monitoring performed four times, with seven-point daily self-monitoring of capillary (fingerstick) glucose performed at least 3 days per week.

RESULTS

Approximately 2,700 glucose values were obtained by each subject during 3 months. Linear regression analysis between the A1C and AG values provided the tightest correlations (AG(mg/dl) = 28.7 x A1C - 46.7, R(2) = 0.84, P < 0.0001), allowing calculation of an estimated average glucose (eAG) for A1C values. The linear regression equations did not differ significantly across subgroups based on age, sex, diabetes type, race/ethnicity, or smoking status.

CONCLUSIONS

A1C levels can be expressed as eAG for most patients with type 1 and type 2 diabetes.

A [meso-tetrakis(4-sulfonatophenyl)porphyrinato]zinc(ii) complex as an oral therapeutic for the treatment of type 2 diabetic KKA(y) mice

We prepared and characterized [meso-tetrakis(4-sulfonatophenyl)porphyrinato]zinc(II) ([Zn(tpps)]), and investigated its in vitro insulin-mimetic activity and in vivo hypoglycemic effect in type 2 diabetic KKA(y) mice. The results were compared with those of previously proposed insulin-mimetic zinc(II) complexes and zinc sulfate (ZnSO(4)). The in vitro insulin-mimetic activity of [Zn(tpps)] was considerably better than that of bis(allixinato)zinc(II) ([Zn(alx)(2)]), bis(maltolato)zinc(II) ([Zn(mal)(2)]), bis(2-aminomethylpyridinato)zinc(II) ([Zn(2-ampy)(2)](2+)), and ZnSO(4). In particular, the order of in vitro insulin-mimetic activity of the complexes was determined to be: [Zn(tpps)]>[Zn(alx)(2)]>[Zn(mal)(2)]>[Zn(2-ampy)](2+)>ZnSO(4). [Zn(tpps)] normalized the hyperglycemia of KKA(y) mice within 21 days when administered orally at doses of 10-20 mg (0.15-0.31 mmol) Zn per kg body mass for 28 days. In addition, metabolic syndromes such as insulin resistance, the degree of renal disturbance, and the degree of liver disturbance were significantly improved in [Zn(tpps)]-treated KKA(y) mice relative to those administered with saline and ZnSO(4). The improvement in diabetes was validated by the results of oral glucose-tolerance tests and the decrease in the HbA(1c) level observed. In contrast, ZnSO(4) and the ligand H(2)tpps did not lower the elevated blood glucose level under the same experimental conditions. Based on these observations, [Zn(tpps)] is proposed to be the first orally active zinc(II)-porphyrin complex for the efficacious treatment of not only type 2 diabetes but also metabolic syndromes in animals.

Glycated albumin is a better indicator for glucose excursion than glycated hemoglobin in type 1 and type 2 diabetes

To determine the impact of blood glucose profile, involving fluctuation and excursion of blood glucose levels, on glycated proteins, we evaluated the association among the daily profile of blood glucose, and glycated albumin (GA) and HbA1c levels in patients with type 1 diabetes (n = 93) and type 2 diabetes (n = 75). GA levels were strongly correlated with HbA1c levels in type 1 (r = 0.85, P<0.0001) and type 2 diabetes (r = 0.61, P<0.0001), respectively. HbA1c levels were similar between patients with type 1 and type 2 diabetes, while GA levels were significantly higher in type 1 diabetes. Thus the ratio of GA levels to HbA1c levels was significantly higher in type 1 diabetes than that in type 2 diabetes (3.32 0.36 vs. 2.89 0.44, p<0.001). The degrees of GA levels and HbA1c levels correlated with maximum and mean blood glucose levels in patients with type 1 and type 2 diabetes. Stepwise multivariate analysis revealed that GA levels independently correlated with maximum blood glucose levels in type 1 diabetes (F = 43.34, P<0.001) and type 2 diabetes (F = 41.57, P<0.001). HbA1c levels also independently correlated with maximum blood glucose levels in type 1 diabetes (F = 34.78, P<0.001), as well as being correlated with mean blood glucose levels in type 2 diabetes (F = 11.28, P<0.001). In summary, GA could be a better marker for glycemic control than glycated hemoglobin in diabetic patients, especially for evaluating glycemic excursion, which is considered to be a major cause of diabetic angiopathy.

Comparison of glycated albumin and hemoglobin A(1c) levels in diabetic subjects on hemodialysis

Glycated albumin is thought to more accurately reflect glycemic control in diabetic hemodialysis patients than hemoglobin A(1c) because of shortened red cell survival. To test this, glycated hemoglobin and albumin levels were measured in blood samples collected from 307 diabetic subjects of whom 258 were on hemodialysis and 49 were without overt renal disease. In diabetic subjects with renal disease, relative to those without, the mean serum glucose and glycated albumin concentrations were significantly higher while hemoglobin A(1c) tended to be lower. The glycated albumin to hemoglobin A(1c) ratio was significantly increased in dialysis patients compared with the controls. Hemoglobin A(1c) was positively associated with hemoglobin and negatively associated with the erythropoietin dose in hemodialysis patients, whereas these factors and serum albumin did not significantly impact glycated albumin levels. Using best-fit multivariate models, dialysis status significantly impacted hemoglobin A(1c) levels without a significant effect on glycated albumin. Our results show that in diabetic hemodialysis patients, hemoglobin A(1c) levels significantly underestimate glycemic control while those of glycated albumin more accurately reflect this control.

Endocrine assessments during critical illness

The evaluation of hormonal status in critically ill patients is challenging and has many pitfalls. This article reviews proper assessment of glycemic status AND adrenal and thyroid function during critical care.

Desirable performance standards for HbA(1c) analysis - precision, accuracy and standardisation: consensus statement of the Australasian Association of Clinical Biochemists (AACB), the Australian Diabetes Society (ADS), the Royal College of Pathologists of Australasia (RCPA), Endocrine Society of Australia (ESA), and the Australian Diabetes Educators Association (ADEA)

BACKGROUND

HbA(1c) (glycohaemoglobin) is universally used in the ongoing monitoring of all patients with diabetes. There are many % HbA(1c) target control rating recommendations by national, regional and international expert bodies for diabetes patients and these are variable around the world. General patient target control ratings are currently most often recommended as either <6.5% or <7.0% HbA(1c), with <6.0% HbA(1c) stated for individual patients where clinically possible. This necessitates very precise HbA(1c) assays and the same patient values, irrespective of HbA(1c) method or area of the world.

METHODS

HbA(1c) targets recommended by major expert groups and published HbA(1c) assay precision (coefficient of variation, %CV) levels have been detailed. These have been compared with published biological variation levels and with calculated HbA(1c) error ranges at various HbA(1c) levels and %CV levels. In addition, these have been compared with the analytical precision necessary to differentiate between the upper limit of the normal range for HbA(1c) and targets recommended by expert groups for diabetes control.

RESULTS

Intralaboratory analytical CVs of <2% are necessary and are achievable on automated HPLC analysers, and are supported on grounds of both clinical need and biological variation, as well as the need to differentiate the national, regional and international target recommendations from the upper limit of the normal range (<6.0% HbA(1c) level).

CONCLUSIONS

Routine methods with tight long-term imprecision with CVs of <2% are recommended. International HbA(1c) targets essentially require that all HbA(1c) methods be precise, and have minimal standardisation bias and minimal methodological interferences in individual patients.

Relationship between glycated haemoglobin levels and mean glucose levels over time

AIMS/HYPOTHESIS

HbA(1c), expressed as the percentage of adult haemoglobin that is glycated, is the most widely used measure of chronic glycaemia. Achieving near-normal HbA(1c) levels has been shown to reduce long-term complications and the HbA(1c) assay is recommended to determine whether treatment is adequate and to guide adjustments. However, daily adjustments of therapy are guided by capillary glucose levels (mmol/l). We determined the relationship between an accurate measure of mean glucose levels over time and the HbA(1c) level, and whether HbA(1c) can be expressed in the same units as self-monitoring results.

METHODS

Twenty-two participants with diabetes and three non-diabetic participants were included in this longitudinal observational study. Mean glucose levels were measured by continuous glucose monitoring (CGM), which measures interstitial glucose levels every 5 min, for 12 weeks. Capillary measurements were obtained four times per day to confirm the accuracy of CGM. HbA(1c) was measured at baseline and every 4 weeks.

RESULTS

The HbA(1c) results at weeks 8 and 12 correlated strongly (r = 0.90) with the CGM results during the preceding 8 and 12 weeks. A curvilinear (exponential) relationship and a linear regression captured the relationship with similarly high correlations, which allowed transformation of HbA(1c) values to a calculated mean glucose level.

CONCLUSIONS AND INTERPRETATION

HbA(1c) correlates closely with a complete measure of average glycaemia over the preceding 8-12 weeks. The translation of HbA(1c) to an average glucose level for reporting and management purposes is feasible.

Can we prevent diabetic ketoacidosis in children?

Diabetic ketoacidosis (DKA) is an acute potentially life-threatening complication of diabetes affecting more than 100,000 persons annually in the United States. Although major advances have improved diabetes care, DKA remains the leading cause of hospitalization, morbidity, and death in youth with type 1 diabetes (T1D). As the majority of patients presenting with DKA have established diabetes, it is important to address outpatient educational approaches directed at sick-day management and early identification and treatment of impending DKA. Teaching and reinforcement of sick-day rules involves improved self-care with consistent self-monitoring of blood glucose and ketones, and timely administration of supplemental insulin and fluids. DKA as an initial manifestation of T1D may be less amendable to prevention except with an increased awareness by the lay and medical communities of the symptoms of diabetes and surveillance in high-risk populations potentially identified by family history or genetic susceptibility. New technologies that can detect the blood ketone 3beta-hydroxybutyrate (3beta-OHB) instead of traditional urine ketones appears to provide opportunity for early identification and treatment of impending DKA leading to reduced need for hospitalization and potential cost-savings.

The utility of fasting plasma glucose in predicting glycosylated hemoglobin in type 2 diabetes

BACKGROUND

Access to glycosylated hemoglobin (HbA1c) assays in clinical practice remains limited. We investigated the relationship of fasting plasma glucose and HbA1c to determine optimal glucose levels for predicting HbA1c.

PATIENTS AND METHODS

We retrospectively analyzed data on 2888 patients with type 2 diabetes mellitus aged >or=20 years using a linear regression of HbA1c against fasting plasma glucose. A receiver-operating characteristic analysis was used to determine optimal cut-points for fasting glucose in relation to HbA1c, area under the curve, sensitivity and specificity, and 95% confidence intervals (CI) for each cut-point.

RESULTS

The mean (standard deviation) for the age of patients was 52+/-11.6 years. The average HbA1c was 8.9+/-2.46% and mean fasting plasma glucose was 10.1+/-3.62 mmol/L. The prevalence of HbA1c >or=7.0% and >6.5% was 76% and 82%, respectively. Overall, fasting plasma glucose and HbA1c were linearly correlated (r=0.62, P=0.001). A fasting plasma glucose of >9.0 mmol/L predicted HbA1c >or=7.0% with an area under the curve = 0.807 (95% CI, 0. 0.794 to 0.821), while fasting plasma glucose >8.2 mmol/L predicted HbA1c >6.5%, with an area under the curve = 0.805 (95% CI, 0.791 to 0.818). The sensitivity of both cut-points was 64.5% and 70.7%, the specificity was 82.7% and 76.4%, the positive likelihood ratio was 3.73 and 2.99, and the positive predictive value was 92.2% and 93.2%, respectively.

CONCLUSION

When HbA1c determination is not available, fasting plasma glucose levels may be used to identify patients with uncontrolled type 2 diabetes and initiate timely intensification of therapy to avoid long- term complications of diabetes.

Effect of chromium supplementation on glucose metabolism and lipids: a systematic review of randomized controlled trials

OBJECTIVE

A systematic review of the effect of chromium supplementation on glucose metabolism and lipid levels.

RESEARCH DESIGN AND METHODS

A literature search was conducted in MEDLINE and the Commonwealth Agricultural Bureau. Eligible studies were English language randomized controlled trials of chromium supplement intake > or = 3 weeks, with > or = 10 participants receiving chromium. All trials with glucose metabolism outcomes and trials of individuals with diabetes or glucose intolerance for lipid outcomes were included. Meta-analyses were performed as appropriate.

RESULTS

Forty-one studies met criteria, almost half of which were of poor quality. Among participants with type 2 diabetes, chromium supplementation improved glycosylated hemoglobin levels by -0.6% (95% CI -0.9 to -0.2) and fasting glucose by -1.0 mmol/l (-1.4 to -0.5) but not lipids. There was no benefit in individuals without diabetes. There were some indications of dose effect and differences among chromium formulations. Larger effects were more commonly observed in poor-quality studies. The evidence was limited by poor study quality, heterogeneity in methodology and results, and a lack of consensus on assessment of chromium status.

CONCLUSIONS

No significant effect of chromium on lipid or glucose metabolism was found in people without diabetes. Chromium supplementation significantly improved glycemia among patients with diabetes. However, future studies that address the limitations in the current evidence are needed before definitive claims can be made about the effect of chromium supplementation.

Beneficial effects of eplerenone versus hydrochlorothiazide on coronary circulatory function in patients with diabetes mellitus

CONTEXT

Impaired coronary circulatory function predicts cardiovascular events, the leading cause of death in patients with diabetes mellitus. Aldosterone causes cardiovascular injury and is not suppressed by chronic angiotensin converting enzyme (ACE) inhibitor therapy.

OBJECTIVE

Our objective was to assess whether mineralocorticoid receptor activation contributes to coronary circulatory dysfunction in patients with diabetes who are already receiving ACE inhibitor therapy.

DESIGN AND SETTING

A randomized, double-blind, crossover study with an intervening washout period of at least 4 wk was conducted with ambulatory patients from the community.

PATIENTS

Patients included 16 subjects (11 men, eight Caucasians; mean age, 53 yr; mean body mass index, 38.0 kg/m2) with diabetes and albuminuria but without clinical cardiovascular disease.

INTERVENTIONS

ACE inhibitors were switched to enalapril 20 mg daily, and other antihypertensives were discontinued. Amlodipine 5-10 mg daily was added to achieve blood pressures less than 130/80 mm Hg. Subjects then received, in random order, 6 wk of the mineralocorticoid receptor antagonist eplerenone 50 mg (with placebo pill) daily and 6 wk of another diuretic, hydrochlorothiazide 12.5 mg (with potassium 10 mEq) daily.

MAIN OUTCOME MEASURES

Before and after each 6-wk treatment period, we measured coronary circulatory function (adenosine-stimulated myocardial perfusion reserve) and endothelial function (brachial artery reactivity and peripheral arterial tonometry).

RESULTS

The eplerenone and hydrochlorothiazide groups had similar blood pressures, serum potassium, glycemia, and endothelial function. Although pretreatment myocardial perfusion reserve did not differ between groups, myocardial perfusion reserve was significantly higher after eplerenone than after hydrochlorothiazide (median 1.57 vs. 1.30; P = 0.03).

CONCLUSIONS

Mineralocorticoid receptor blockade improves coronary circulatory function compared with hydrochlorothiazide in patients with diabetes already receiving ACE inhibitor therapy.

Screening Copenhagen school children at risk of type 2 diabetes mellitus using random capillary blood glucose

AIM

To screen adolescents at risk of type 2 diabetes mellitus (T2DM) using random capillary blood glucose (RCBG).

METHODS

Ninth grade pupils who were overweight and/or had a family history of T2DM were offered to have RCBG measured and were referred for further investigation if the value was > or = 7.8 mmol/L.

RESULTS

Two thousand four hundred and eleven pupils were examined, 19% were overweight, 4% being obese. 589 met inclusion criteria and 384 participated. Ethnic minorities and pupils in low socio-economic school-areas (SESA) were significantly more overweight than ethnic Danes and pupils in high SESA. Compared to ethnic Danish pupils, the relative risk of having a positive parent history of T2DM was increased five-fold for ethnic Turkish and Arab pupils and 13-fold for ethnic Pakistani pupils. One pupil had a diagnosed T2DM. Two had elevated RCBG values. One of these had an undiagnosed T2DM.

CONCLUSION

Our study shows a high prevalence of overweight adolescents in Copenhagen, especially in school areas with low socio-economic standard and in pupils with Turkish, Pakistani and Arab ethnicity. Only three out of the 10 pupils with the highest risk participated. New strategies to reach and motivate risk groups to follow health recommendations and new methods of screening should be developed.

Antidiabetic Activity of the Orally Effective Vanadyl-Poly (γ-Glutamic Acid) Complex in Streptozotocin(STZ)-induced Type 1 Diabetic Mice

Newly synthesized vanadyl-poly(γ-glutamic acid) complex (VO-γ-PGA) with a VO(O4) coordination mode was found to have potent antidiabetic activity in streptozotocin (STZ)-induced type 1 diabetic mice (STZ-mice), compared with that of a solution containing only vanadyl sulfate, VOSO 4. This was the first example of orally active vanadyl complex of γ-PGA for treating STZ-mice. To better define its efficacy, we examined here the effects of VO-γ-PGA treatment in STZ-mice by oral administration at the dose of 10 mg V/kg body mass for a longer period time than our previous study. The improvement in diabetic states in STZ-mice compared with saline-treated nondiabetic normal Std ddY mice. It was found that the elevated blood glucose levels in STZ-mice significantly decreased after 3 days and sustained the normalized blood glucose level around 180—200 mg/dL (10—11.1 mM) for the last 14 days, which is close to the blood glucose levels 100—200 mg/dL (5.6—11.1 mM) in nondiabetic normal Std ddY mice. The improvement in diabetes was strongly corelated by the improvement in oral glucose tolerance ability, glycosylated hemoglobin (HbA1c) levels and blood pressure, and serum parameters. The present results confirmed that VO-γ-PGA complex is a promising, orally active insulin-mimetic agent to treat type 1 diabetic mice.

Recent progress in analytical instrumentation for glycemic control in diabetic and critically ill patients

Implementing strict glycemic control can reduce the risk of serious complications in both diabetic and critically ill patients. For this reason, many different analytical, mainly electrochemical and optical sensor approaches for glucose measurements have been developed. Self-monitoring of blood glucose (SMBG) has been recognised as being an indispensable tool for intensive diabetes therapy. Recent progress in analytical instrumentation, allowing submicroliter samples of blood, alternative site testing, reduced test time, autocalibration, and improved precision, is comprehensively described in this review. Continuous blood glucose monitoring techniques and insulin infusion strategies, developmental steps towards the realization of the dream of an artificial pancreas under closed loop control, are presented. Progress in glucose sensing and glycemic control for both patient groups is discussed by assessing recent published literature (up to 2006). The state-of-the-art and trends in analytical techniques (either episodic, intermittent or continuous, minimal-invasive, or noninvasive) detailed in this review will provide researchers, health professionals and the diabetic community with a comprehensive overview of the potential of next-generation instrumentation suited to either short- and long-term implantation or ex vivo measurement in combination with appropriate body interfaces such as microdialysis catheters.

The inappropriate use of HbA1c testing to monitor glycemia: is there evidence in laboratory data?

RATIONALE, AIMS AND OBJECTIVES

Diabetes is a chronic illness and have relatively high prevalence. Glycemic control is fundamental to the management of diabetes. Hemoglobin A1c (HbA1c) is a commonly used laboratory test to monitor glycemia and to manage diabetes. This study aimed to assess the appropriateness of the frequency of HbA1c test order with respect to the commonly approved guidelines for monitoring glycaemia of patients.

METHODS

To assess the rate of inappropriate test orders, laboratory records of HbA1c tests ordered between 2002 and 2004 were evaluated. Inappropriate orders were defined as any order for a given patient that takes place within a 29- or 89-day-period following the previous HbA1c order. The effects of various parameters, like ordering clinics, the first HbA1c level, or the on-line availability of test results on test ordering were evaluated.

RESULTS

Evaluation of test intervals showed that 10.3% of all orders and 33.8% of the inpatients' orders were performed within 29 days, 35.5% of all orders and 55% of the inpatients' orders were within 89 days.

CONCLUSIONS

Inappropriate laboratory utilization of HbA1c testing is very common especially in the inpatient clinics. We think that the application of the guidelines may decrease unnecessary health expenditure.

Assessing glycemic control with self-monitoring of blood glucose and hemoglobin A(1c) measurements

Hemoglobin A(1c) (HbA(1c)) is the gold standard for monitoring glycemic control and serves as a surrogate for diabetes-related complications. Although HbA(1c) measures mean glycemic exposure during the preceding 2 to 3 months, it does not provide iInformation about day-to-day changes in glucose levels. Self-monitoring of blood glucose represents an important adjunct to HbA(1c) because it can distinguish among fasting, preprandial, and postprandial hyperglycemia; detect glycemic excursions; identify hypoglycemia; and provide immediate feedback to patients about the effect of food choices, activity, and medication on glycemic control.

Determinants of Arterial Wall Stiffness and Peripheral Artery Occlusive Disease in Nondiabetic Hemodialysis Patients

Aortic pulse wave velocity (Ao-PWV) and ankle-brachial blood pressure index (ABPI) are significant prognostic factors in patients with end-stage renal disease (ESRD). Diabetes mellitus (DM) promotes changes in arterial walls, including marked increases in Ao-PWV and decreases in ABPI. To determine the prevalence of peripheral arterial occlusive disease (PAOD) as well as the clinical variables useful in predicting these changes in nondiabetic patients with ESRD undergoing hemodialysis (HD), we performed a cross-sectional study in a cohort of 143 patients. Ao-PWV and ABPI were measured simultaneously and compared with several annual biochemical measurements and other clinical variables. The prevalence of PAOD in our cohort was 30.5%. In univariate regression analysis, Ao-PWV correlated positively with age, heart rate (HR), blood pressure (BP), pulse pressure (PP) and HbA1c, and negatively with serum albumin and ABPI. ABPI correlated negatively with age, HD duration, systolic BP, PP, low-density lipoprotein (LDL) cholesterol and hypersensitive C-reactive protein (hs-CRP), and positively with serum albumin and bone mineral density. In a step-down multiple regression analysis, HbA1c was identified as an independent determinant of Ao-PWV along with age, HD duration, HR and mean BP, while hs-CRP was an independent contributor to ABPI along with age, HD duration, PP and LDL cholesterol. Our results suggest that HD promotes aortic wall stiffness and PAOD progression. We recommend the monitoring of HbA1c to allow the prediction of aortic wall stiffness in nondiabetic ESRD patients. Our results did not confirm the influence of insulin resistance on the development of arterial sclerosis lesions.

Self-reported medication and lifestyle adherence in Hungarian patients with Type 2 diabetes

BACKGROUND

Type 2 diabetes is a complex disorder that requires the patient to pay constant attention to diet, physical activity, glucose monitoring and medication.

OBJECTIVE

To evaluate the medication, lifestyle adherence and factors associated to these in Type 2 diabetes in Hungarian patients.

SETTING

Fourteen community pharmacies in Hungary between March and May 2004.

METHOD

A questionnaire was given to every tenth Type 2 diabetic patient who presented to one of the 14 pharmacies included in this study with a prescription for oral antidiabetics, oral antidiabetics and insulin or exclusively insulin. For the latter two groups, the prerequisite for inclusion in the study was also that their diabetes had developed after the age of 35 and that at some in their treatment regimen they had taken only oral antidiabetics. These latter two criteria were controlled in the patient's general practitioners' (GP) database. General and diabetes-related data were collected in the questionnaire, and the adherence and lifestyle of the participant were assessed. An adapted and validated Hungarian version of the EQ-5D (EuroQol Group, 1993) quality-of-life questionnaire was also included. Descriptive and chi(2) test statistical methods and two sample t-test were used. A significance level of P<0.05 was considered to be significant.

MAIN OUTCOME MEASURE

Patient self-reported adherence to diet, physical activity, self monitoring of blood glucose, purchasing of drug(s), drug regimen, association of demographic factors, treatment, lifestyle and quality of life on adherence.

RESULTS

Of the 220 questionnaires distributed to diabetic patients, 151 were returned, of which 142 were evaluated (nine did not satisfy the above-mentioned inclusion criteria). With respect to the factors assessed, sub-optimal adherence was assessed for: diet (76.8%), physical activity (33.8%), self-monitoring of blood glucose (81%), drug purchasing (20.4%) and drug taking (52.1%). Smokers comprised 14.8% of the respondents, while 8.5% were heavy drinkers. Fewer than five meals a day were eaten by 46.5% of the patients, and about 43.6% of the patients did not self-monitor blood glucose. The results indicate few significant associations between at least one of the four main areas of adherence (diet, physical activity, purchasing of drug(s), drug regimen) and body mass index, GP consultation frequency, quality-of-life parameters and EQ-5D index.

CONCLUSION

The adherence of Hungarian Type 2 diabetics in some areas does not reach optimal levels, especially for diet, self-monitoring, drug purchasing and adherence to drug taking.

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.

Poor glycated haemoglobin control and adverse pregnancy outcomes in type 1 and type 2 diabetes mellitus: systematic review of observational studies

BACKGROUND

Glycaemic control in women with diabetes is critical to satisfactory pregnancy outcome. A systematic review of two randomised trials concluded that there was no clear evidence of benefit from very tight versus tight glycaemic control for pregnant women with diabetes.

METHODS

A systematic review of observational studies addressing miscarriage, congenital malformations and perinatal mortality among pregnant women with type 1 and type 2 diabetes was carried out. Literature searches were performed in MEDLINE, EMBASE, CINAHL and Cochrane Library. Observational studies with data on glycated haemoglobin (HbA1c) levels categorised into poor and optimal control (as defined by the study investigators) were selected. Relative risks and odds ratios were calculated for HbA1c and pregnancy outcomes. Adjusted relative risk estimates per 1-percent decrease in HbA1c were calculated for studies which contained information on mean and standard deviations of HbA1c.

RESULTS

The review identified thirteen studies which compared poor versus optimal glycaemic control in relation to maternal, fetal and neonatal outcomes. Twelve of these studies reported the outcome of congenital malformations and showed an increased risk with poor glycaemic control, pooled odds ratio 3.44 (95%CI, 2.30 to 5.15). For four of the twelve studies, it was also possible to calculate a relative risk reduction of congenital malformation for each 1-percent decrease in HbA1c, these varied from 0.39 to 0.59. The risk of miscarriage was reported in four studies and was associated with poor glycaemic control, pooled odds ratio 3.23 (95%CI, 1.64 to 6.36). Increased perinatal mortality was also associated with poor glycaemic control, pooled odds ratio 3.03 (95%CI, 1.87 to 4.92) from four studies.

CONCLUSION

This analysis quantifies the increase in adverse pregnancy outcomes in women with diabetes who have poor glycaemic control. Relating percentage risk reduction in HbA1c to relative risk of adverse pregnancy events may be useful in motivating women to achieve optimal control prior to conception.

Normal but increasing hemoglobin A1c levels predict progression from islet autoimmunity to overt type 1 diabetes: Diabetes Autoimmunity Study in the Young (DAISY)

OBJECTIVE

The aim of this study was to assess the utility of hemoglobin A1c (HbA1c) measurements in the early detection of clinical type 1 diabetes during prospective follow-up of children with islet autoimmunity.

METHODS

The Diabetes Autoimmunity Study in the Young (DAISY) has followed for development of islet autoimmunity and diabetes general population newborns carrying human leukocyte antigen (HLA) genotypes conferring risk for type 1 diabetes and young siblings or offspring of people with type 1 diabetes. Testing for autoantibodies was performed at least once in 2234 and twice or more in 1887 children. Among the latter, 100 children tested positive on at least two consecutive visits. To date, 92 children have developed persistent islet autoantibodies to glutamic acid decarboxylase 65 (GAD65), insulin, or insulinoma associated antigen-2 (IA-2) and had at least two subsequent clinic visits. These children had study visits with point-of-care testing for HbA1c and random glucose every 3-6 months and those with random plasma glucose above 11.1 mmol/L or HbA1c above 6.3% were evaluated by a pediatric endocrinologist for clinical diabetes.

RESULTS

During a mean follow-up of 3.4 yr from onset of autoimmunity, 28 children developed type 1 diabetes, at mean age of 6.5 yr. Mean prediagnostic HbA1c was 5.1% [standard deviation (SD) = 0.4%]. In a Cox regression model accounting for changes in values in individuals over time, increase in HbA1c predicted increased risk of progression to type 1 diabetes, hazard ratio = 4.8 (95% confidence interval 3.0-7.7) for each SD of 0.4%, independent of random glucose and number of autoantibodies. Increase in random plasma glucose levels only marginally predicted risk of progression (hazard ratio = 1.4, 95% confidence interval 1.02-1.8, per SD of 1.1 mmol/L).

CONCLUSIONS

Normal but increasing Hb1Ac may be useful in early detection of type 1 diabetes, whereas random plasma glucose levels were less predictive.

Facteurs déterminants du contrôle glycémique des patients diabétiques de type 2 suivis en première ligne

PURPOSE

To determine the factors associated with poor glycemic control in type 2 diabetic patients followed in primary care units in Sousse, Tunisia.

METHODS

A cross-sectional study was conducted on a representative sample of type 2 diabetic patients followed at least two years in primary health care units in Sousse, Tunisia. Data were gathered from three sources: a self-administrated questionnaire, analysis of patient files and HbA1c level. HbA1c level was measured with turbidimetric immunoinhibition assay. Patients were considered well-controlled if glycated hemoglobin (HbA1c) was less than 7%, according to the American Diabetics Association (ADA) recommendations.

RESULTS

The study enrolled 404 type 2 diabetic patients. The mean age was 60.5+/-10.89 years, sex-ratio was 0.5, and mean disease duration 8.7+/-6.1 years. ADA recommendations were met by 16.7% of patients. Multivariate analysis using variables in relation with the patient, his/her family, the disease, the treatment and the health care unit, showed that only poor geographic access to the care center (adjusted OR: 1.89, p=0.009) and Body Mass Index (BMI) less than 30 kg/m2 (adjusted OR: 2.21, p=0.034) were significantly and independently associated with poor glycemic control.

CONCLUSION

Glycemic control in type 2 diabetic patients is poor. It depends strongly on geographic access to health care. Type 2 diabetic patients should be referred, as much as possible, to the nearest health care unit.