Tests of glycemia in diabetes

The Effect of Blood Glucose Self-Monitoring Among Inmates With Diabetes

The increasing prevalence and risk of complications from diabetes necessitate patient participation and attentiveness to select appropriate foods, perform regular physical activity, and be active in diabetes management and self-maintenance. Diabetes is often largely asymptomatic; consequently, early diagnosis and treatment are necessary. Inmates are a unique population challenged by the increased prevalence of chronic conditions including diabetes. Diabetes standards for inmates contain diagnostic and treatment management guidelines that incorporate personal glucose monitoring for insulin users. In December 2009, the Federal Bureau of Prisons initiated a program to distribute glucose meters to insulin-dependent inmates to facilitate self-monitoring blood glucose. The purpose of this study was to evaluate the effect of these glucose meters on hemoglobin A1c levels.

Receptor for Advanced Glycation End-Products Signaling Interferes with the Vascular Smooth Muscle Cell Contractile Phenotype and Function

Increased blood glucose concentrations promote reactions between glucose and proteins to form advanced glycation end-products (AGE). Circulating AGE in the blood plasma can activate the receptor for advanced end-products (RAGE), which is present on both endothelial and vascular smooth muscle cells (VSMC). RAGE exhibits a complex signaling that involves small G-proteins and mitogen activated protein kinases (MAPK), which lead to increased nuclear factor kappa B (NF-κB) activity. While RAGE signaling has been previously addressed in endothelial cells, little is known regarding its impact on the function of VSMC. Therefore, we hypothesized that RAGE signaling leads to alterations in the mechanical and functional properties of VSMC, which could contribute to complications associated with diabetes. We demonstrated that RAGE is expressed and functional in the A7r5 VSMC model, and its activation by AGE significantly increased NF-κB activity, which is known to interfere with the contractile phenotype of VSMC. The protein levels of the contraction-related transcription factor myocardin were also decreased by RAGE activation with a concomitant decrease in the mRNA and protein levels of transgelin (SM-22α), a regulator of VSMC contraction. Interestingly, we demonstrated that RAGE activation increased the overall cell rigidity, an effect that can be related to an increase in myosin activity. Finally, although RAGE stimulation amplified calcium signaling and slightly myosin activity in VSMC challenged with vasopressin, their contractile capacity was negatively affected. Overall, RAGE activation in VSMC could represent a keystone in the development of vascular diseases associated with diabetes by interfering with the contractile phenotype of VSMC through the modification of their mechanical and functional properties.

Short-term high-intensity interval and moderate-intensity continuous training reduce leukocyte TLR4 in inactive adults at elevated risk of type 2 diabetes

Exercise can have anti-inflammatory effects in obesity, but the optimal type and intensity of exercise are not clear. This study compared short-term high-intensity interval training (HIIT) with moderate-intensity continuous training (MICT) in terms of improvement in cardiorespiratory fitness, markers of inflammation, and glucose control in previously inactive adults at elevated risk of developing type 2 diabetes. Thirty-nine inactive, overweight/obese adults (32 women) were randomly assigned to 10 sessions over 2 wk of progressive HIIT (n = 20, four to ten 1-min sessions at ∼90% peak heart rate, 1-min rest periods) or MICT (n = 19, 20-50 min at ∼65% peak heart rate). Before and 3 days after training, participants performed a peak O2 uptake test, and fasting blood samples were obtained. Both HIIT (1.8 ± 0.4 vs. 1.9 ± 0.4 l/min, pre vs. post) and MICT (1.8 ± 0.5 vs. 1.9 ± 0.5 l/min, pre vs. post) improved peak O2 uptake (P < 0.001) and lowered plasma fructosamine (P < 0.05). Toll-like receptor (TLR) 4 (TLR4) expression was reduced on lymphocytes and monocytes after both HIIT and MICT (P < 0.05) and on neutrophils after MICT (P < 0.01). TLR2 on lymphocytes was reduced after HIIT and MICT (P < 0.05). Plasma inflammatory cytokines were unchanged after training in both groups, but MICT led to a reduction in fasting plasma glucose (P < 0.05, 5.9 ± 1.0 vs. 5.6 ± 1.0 mmol/l, pre vs. post). Ten days of either HIIT or MICT can improve cardiorespiratory fitness and glucose control and lead to reductions in TLR2 and TLR4 expression. MICT, which involved a longer duration of exercise, may be superior for reducing fasting glucose.

Alternative biomarkers for assessing glycemic control in diabetes: fructosamine, glycated albumin, and 1,5-anhydroglucitol

The growing attention to alternative glycemic biomarkers including fructosamine, glycated albumin (GA), 1,5-anhydroglucitol (1,5-AG), is attributable to the limitations of the glycated hemoglobin (HbA1c) assay. It is important to recognize the conditions in which HbA1c levels may be difficult to interpret. Serum fructosamine and GA have been proposed useful tools for monitoring of short-term glycemic control. These biomarkers not only reflect well glycemic control in hematologic disorder, but also represent postprandial glucose fluctuation. Serum 1,5-AG may be useful for estimating within-day glucose variation. Use of these nontraditional tests can be more helpful in the management of diabetes as complement traditional measures. Further larger cohort studies are warranted to determine whether nontraditional biomarkers have potential utility for early diagnosis, management of diabetes, and prevention of diabetic complications.

A systematic review and meta-analysis of beta-glucan consumption on glycemic control in hypercholesterolemic individuals

Evidence from animal and observational studies has supported the beneficial effects of beta-glucan intake on glycemic control, but intervention studies in hypercholesterolemic crowd have generated mixed results and have not been systematically examined. In the present study, we aimed to quantitatively evaluate the relation between beta-glucan consumption from oats or barley on glycemic control in hypercholesterolemic individuals. A systematic literature review was conducted for relevant published randomized controlled trials studies (RCTs) in electronic databases through July 2014. Twelve trials with a total of 603 subjects were included in the meta-analysis. Beta-glucan consumption did not significantly affect measures of glycemic control. Summary estimates of weighted mean differences (WMD) and 95% confidence interval was 0.05 mmol/L (-0.11, 0.02) for fasting glucose concentration and 0.75 pmol/L (-1.82, 3.32) for fasting insulin concentrations. In conclusion, there was not a significant overall effect of beta-glucan intake on improvements of fasting glucose and insulin concentrations in hypercholesterolemic subjects.

Advancing the development of glycated protein biosensing technology: next-generation sensing molecules

Research advances in biochemical molecules have led to the development of convenient and reproducible biosensing molecules for glycated proteins, such as those based on the enzymes fructosyl amino acid oxidase (FAOX) or fructosyl peptide oxidase (FPOX). Recently, more attractive biosensing molecules with potential applications in next-generation biosensing of glycated proteins have been aggressively reported. We review 2 such molecules, fructosamine 6-kinase (FN6K) and fructosyl amino acid-binding protein, as well as their recent applications in the development of glycated protein biosensing systems. Research on FN6K and fructosyl amino acid-binding protein has been opening up new possibilities for the development of highly sensitive and proteolytic-digestion-free biosensing systems for glycated proteins.

Coronary atherosclerosis is already ongoing in pre-diabetic status: Insight from intravascular imaging modalities

Diabetes mellitus is a powerful risk factor of coronary artery disease (CAD), leading to death and disability. In recent years, given the accumulating evidence that prediabetes is also related to increasing risk of CAD including cardiovascular events, a new guideline has been proposed for the treatment of blood cholesterol for primary prevention of cardiovascular events. This guideline recommends aggressive lipid-lowering statin therapy for primary prevention in diabetes and other patients. The ultimate goal of patient management is to inhibit progression of systemic atherosclerosis and prevent fatal cardiovascular events such as acute coronary syndrome (ACS). Because disruption of atherosclerotic coronary plaques is a trigger of ACS, the high-risk atheroma is called a vulnerable plaque. Several types of novel diagnostic imaging technologies have been developed for identifying the characteristics of coronary atherosclerosis before the onset of ACS, especially vulnerable plaques. According to coronary angioscopic evaluation, atherosclerosis severity and plaque vulnerability were more advanced in prediabetic than in nondiabetic patients and comparable to that in diabetic patients. In addition, pharmacological intervention by statin therapy changed plaque color and complexity, and the dynamic changes in plaque features are considered plaque stabilization. In this article, we review the findings of atherosclerosis in prediabetes, detected by intravascular imaging modalities, and the therapeutic implications.

Risk Factors and Coping Style Affect Health Outcomes in Adults With Type 2 Diabetes

OBJECTIVE

Most psychosocial interventions among individuals with Type 2 diabetes mellitus (T2DM) target depressive symptoms (DSs) rather than causal antecedents that lead to DSs or affect health-related quality of life (HrQoL). This research investigated a conceptual model of the effects of risk factors and coping styles on HrQoL and DSs in patients with T2DM.

METHOD

A descriptive, correlational design was used with a convenience sample of 241 adults with T2DM aged ≥ 20 years recruited from a hospital metabolic outpatient department. Data were collected using a demographic questionnaire, the modified Ways of Coping Checklist, the Center for Epidemiological Studies Depression Scale, the Short Form 36 Health Survey, and physiological examination. HbA1C was collected from participants' medical records. Structural equation modeling techniques were used to analyze relationships among risk factors, mediators, and HrQoL.

RESULTS

Younger age, more education, and longer duration of diabetes predicted better physical quality of life. Duration of diabetes and three coping styles predicted DSs. Longer duration of diabetes and lower fasting glucose predicted better mental quality of life. Three coping styles acted as mediators between risk factors and health, that is, active and minimizing styles promoted positive outcomes, while avoidance promoted negative outcomes.

CONCLUSIONS

This integrated model provides a holistic picture of how risk factors and coping style influence HrQoL and DSs in individuals with T2DM. Nurses could use active coping strategies in cognitive behavioral therapy to enhance glycemic control in patients with T2DM.

Association between hemoglobin A1c and all-cause mortality: results of the mortality follow-up of the German National Health Interview and Examination Survey 1998

OBJECTIVE

This study examined the association of HbA1c-defined glycemic status and continuous HbA1c with all-cause mortality.

RESEARCH DESIGN AND METHODS

The study population comprised 6,299 participants (aged 18-79 years) of the German National Health Interview and Examination Survey 1998, who were followed up for mortality for an average of 11.6 years. Glycemic status was defined as known diabetes (self-reported diagnosis or intake of antidiabetic medication) and based on HbA1c levels according to American Diabetes Association diagnostic criteria as undiagnosed diabetes (≥6.5% [≥48 mmol/mol]), prediabetes with very high (6.0-6.4% [42-46 mmol/mol]) or high diabetes risk (5.7-5.9% [39-41 mmol/mol]), and normoglycemia (<5.7% [<39 mmol/mol]). Associations between glycemic status and mortality were examined by Cox regression adjusting for age, sex, education, lifestyle factors, anthropometric measures, and history of chronic diseases (reference: normoglycemia). Spline models were fitted to investigate associations between continuous HbA1c and mortality among participants without known diabetes.

RESULTS

Excess mortality risk was observed for participants with known diabetes (hazard ratio 1.41 [95% CI 1.08-1.84]) and undiagnosed diabetes (1.63 [1.23-2.17]) but not for those with high (1.02 [0.80-1.30]) or very high diabetes risk (0.87 [0.67-1.13]). Spline models revealed a U-shaped association, with lowest risk at HbA1c levels 5.4-5.6% (36-38 mmol/mol) and a significantly increased risk at ≤5.0% (≤31 mmol/mol) and ≥6.4% (≥46 mmol/mol).

CONCLUSIONS

Unlike known and undiagnosed diabetes, HbA1c levels in the prediabetic range were not associated with an increased mortality risk. The observed U-shaped relationship adds to existing evidence that not only high but also low HbA1c levels might be associated with all-cause mortality.

Development and Validation of the Perception of Self-Monitoring of Blood Glucose Scale in Insulin-Treated Patients With Diabetes

Background and Purpose: The Perception of Self-Monitoring of Blood Glucose (P-SMBG) scale was developed and validated to assess perceptions of self-monitoring of blood glucose (SMBG) in insulin-treated patients with diabetes. Method: An initial 68-item version of the P-SMBG has been evaluated by a panel of professionals and patients. A sample of 375 patients tested the revised scale. Results: Factor analysis suggested a 19-item scale and a 2-factor structure, separating negatively and positively worded items. Cronbach’s alpha was .84 and .72, and the intraclass correlation coefficient was .66 and .57, respectively for both factors. Item–total correlations were in the range of .23–.66. Convergent/divergent validity was confirmed for the negatively worded items. Conclusions: The final P-SMBG scale (21 items) can be used to assess positive and negative perceptions of SMBG in insulin-treated patients with diabetes.

Monitoring glycemia in diabetes

Monitoring of glycemic control is a key component of the diabetes treatment plan. Patients who are not meeting targets often require more intensive monitoring, ranging from frequent self-monitored glucose to continuous glucose monitoring in order to facilitate medication and lifestyle changes. However, more intensive monitoring demands more training and a structured plan for interpretation and use of the data. Better patient and provider tools to support decision-making and progress toward an artificial pancreas may help to alleviate this burden.

Sleep, health-related quality of life, and functional outcomes in adults with diabetes

PURPOSE

This study explored the association of sleep quality with physical and mental health-related quality of life (HRQoL) and functional outcomes in 116 participants with type 2 diabetes.

METHODS

The study is a secondary analysis of baseline data from a clinical trial that examined treatment of obstructive sleep apnea on physical activity and glucose control. Instruments included the Pittsburgh Sleep Quality Index, Medical Outcomes Short-Form Physical Component and Mental Component Scores, and Functional Outcomes of Sleep Questionnaire.

RESULTS

Higher physical HRQoL was significantly associated with better sleep quality and improved functional outcomes of increased activity and productivity. Higher mental HRQoL was associated with improved sleep quality and improved functional outcomes of increased activity, social interactions, vigilance, and productivity. Poor sleep quality was a predictor of decreased functional outcomes while controlling for age, race, education, BMI, marital status and physical and mental HRQoL.

CONCLUSION

Poor sleep quality is associated with negative physical, mental, and functional outcomes in adults with type 2 diabetes.

Effects of hemoglobin variants on hemoglobin a1c values measured using a high-performance liquid chromatography method

Hemoglobin A1c (HbA1c) is routinely used to monitor long-term glycemic control and for diagnosing diabetes mellitus. However, hemoglobin (Hb) gene variants/modifications can affect the accuracy of some methods. The potential effect of Hb variants on HbA1c measurements was investigated using a high-performance liquid chromatography (HPLC) method compared with an immunoturbimetric assay. Fasting plasma glucose (FPG) and HbA1c levels were measured in 42 371 blood samples. Samples producing abnormal chromatograms were further analyzed to characterize any Hb variants. Fructosamine levels were determined in place of HbA1c levels when unstable Hb variants were identified. Abnormal HPLC chromatograms were obtained for 160 of 42 371 samples. In 26 samples HbS was identified and HbA1c results correlated with FPG. In the remaining 134 samples HbD, Hb Louisville, Hb Las Palmas, Hb N-Baltimore, or Hb Porto Alegre were identified and HbA1c did not correlate with FPG. These samples were retested using an immunoturbidimetric assay and the majority of results were accurate; only 3 (with the unstable Hb Louisville trait) gave aberrant HbA1c results. Hb variants can affect determination of HbA1c levels with some methods. Laboratories should be aware of Hb variants occurring locally and choose an appropriate HbA1c testing method.

Screening with HbA1c identifies only one in two individuals with diagnosis of prediabetes at oral glucose tolerance test: findings in a real-world Caucasian population

OBJECTIVE

Discordance between HbA1c and OGTT in screening pre-diabetes may occur because of lack of laboratory standardization, distinct underlying pathophysiological processes or different ethnicity. We evaluated HbA1c efficacy for screening OGTT-defined IFG and IGT conditions in a large Caucasian population using the newly revised IFCC protocol.

RESEARCH DESIGN AND METHODS

A total of 501 consecutive subjects were screened for pre-diabetic conditions with OGTT with 75 g of glucose. Testing for HbA1c, lipid profile and fasting insulin levels was also performed. For detecting differences between continuous variables, ANOVA followed by Tukey's honestly significant difference (HSD) post hoc test was used. Logistic regression and ROC curve analysis were also performed for assessing HbA1c screening efficacy.

RESULTS

ROC curve analysis showed that optimal HbA1c cut-off for detecting IFG was 5.6 % (sensitivity of 78 % and specificity of 63 %), while for IGT, the optimal cut-off was 5.9 % (sensitivity of 46 % and specificity of 84 %), with AUCs < 0.8. Screening with HbA1c identified 53.4 % of the 193 patients with IFG and/or IGT diagnosed at OGTT. As regards surrogate markers of insulin resistance, we observed a trend towards higher values of HOMA-IR and lower QUICKI values in subjects with IFG than in those with IGT. Patients with pre-diabetes at both tests had similar values of HOMA and QUICKI, compared with those with altered OGTT only.

CONCLUSIONS

IFCC-aligned HbA1c assay proved scarcely effective in detecting IFG and/or IGT in a large Caucasian population, identifying only half of the patients with abnormal OGTT. Moreover, adding HbA1c screening to OGTT may be of little benefit in identifying subjects with a worse metabolic profile.

Intensive low-glycaemic-load dietary intervention for the management of glycaemia and serum lipids among women with gestational diabetes: a randomized control trial

OBJECTIVE

The present study aimed to compare the effects of a general dietary intervention and an intervention with low glycaemic load (GL) on glycaemic control, blood lipid metabolism and pregnancy outcomes in women with gestational diabetes mellitus.

DESIGN

Participants were randomly assigned to two groups, receiving either an individualized general dietary intervention (Control group) or an intensive low-GL intervention (Low-GL group) every two weeks, from 24-26 weeks of gestation to delivery.

SETTING

The Center of Maternal Primary Care in Guangdong General Hospital, China.

SUBJECTS

Ninety-five women with gestational diabetes mellitus were enrolled from June 2008 to July 2009.

RESULTS

After the intervention, both groups significantly decreased their dietary intakes of energy, fat and carbohydrate. The Low-GL group had significantly lower values for GL (122 v. 136) and glycaemic index (50 v. 54) but greater dietary fibre intake (33 v. 29 g/d) than did the Control group (all P<0·01). Significantly greater decreases in fasting plasma glucose (-0·33 v. -0·02 mmol/l, P<0·01) and 2 h postprandial glucose (-2·98 v. -2·51 mmol/l, P<0·01), significantly lower increases in total cholesterol (0·12 v. 0·23 mmol/l) and TAG (0·41 v. 0·56 mmol/l) and a significantly lower decrease in HDL cholesterol (-0·01 v. -0·11 mmol/l) were also observed in the Low-GL group compared with the Control group (all P<0·05). There were no significant differences in body weight gain, birth weight or other maternal-fetal perinatal outcomes between the two groups.

CONCLUSIONS

The low-GL targeted dietary intervention outperformed the general dietary intervention in glycaemic control and the improvement of blood lipid levels in women with gestational diabetes mellitus.

Glycemic profile of persons with Diabetes mellitus in a home blood glucose self-monitoring program

This retrospective study aimed to analyze the blood capillary glucose at home and the number of hypoglycemic and hyperglycemic episodes presented by persons with Diabetes Mellitus, at the start of, and at least six months after beginning to participate in, the Blood Glucose Self-Monitoring Program. A total of 97 service users with diabetes participated, from a municipality in the non-Metropolitan region of the state of São Paulo. Two spreadsheets were used for recording the blood glucose values at the start of the Program and after a minimum of six months. It was observed that there was an improvement in the postprandial blood glucose level (lunch) and in the very early morning (p<0.05). In relation to hypoglycemic episodes, there was a slight improvement in the mean, from 0.75 at the beginning to 0.49 after a minimum of six months' participation in the Program. The reduction of hyperglycemic episodes was, in the beginning, of 27.88% episodes and, at a minimum of six months' participation in the Program, of 29.15% episodes.

Structured SMBG in early management of T2DM: Contributions from the St Carlos study

Diabetes mellitus type 2 (T2DM) is a global pandemic that will affect 300 million people in the next decade. It has been shown that early and aggressive treatment of T2DM from the onset decreases complications, and the patient’s active role is necessary to achieve better glycemic control. In order to achieve glycemic control targets, an active attitude in patients is needed, and self-monitoring of blood glucose (SMBG) plays a significant role. Nowadays, SMBG has become an important component of modern therapy for diabetes mellitus, and is even more useful if it is performed in a structured way. SMBG aids physicians and patients to achieve a specific level of glycemic control and to prevent hypoglycemia. In addition, SMBG empowers patients to achieve nutritional and physical activity goals, and helps physicians to optimize the different hypoglycemic therapies as demonstrated in the St Carlos study. This article describes the different ways of using this educational and therapeutic tool from the medical point of view as well as from the patient’s perspective.

Misleading hemoglobin A1c levels in a patient with paroxysmal nocturnal hemoglobinuria

OBJECTIVES

We report a case of a patient with diabetes mellitus and unexpectedly low hemoglobin A1c results associated with paroxysmal nocturnal hemoglobinuria (PNH). We review the impact of shortened RBC half-life on the interpretation of hemoglobin A1c levels.

METHODS

Patient history and laboratory test results were obtained from electronic medical records and analyzed.

RESULTS

The patient's hemoglobin A1c declined in parallel to worsening anemia after the diagnosis of PNH. However, elevated serum glucose (random), fructosamine, and glycated albumin suggest ongoing hyperglycemia. Together, these results argue that the decline in hemoglobin A1c was due to decreased RBC survival secondary to PNH.

CONCLUSIONS

Hemoglobin A1c levels must be interpreted with caution in patients with hematologic diseases that change RBC survival. Serum fructosamine and glycated albumin measurements are alternative measures of time-averaged blood glucose control and may be useful in this subset of patients.

Temporal trends of hemoglobin A1c testing

OBJECTIVE

The study of utilization patterns can quantify potential overuse of laboratory tests and find new ways to reduce healthcare costs. We demonstrate the use of distributional analytics for comparing electronic health record (EHR) laboratory test orders across time to diagnose and quantify overutilization.

MATERIALS AND METHODS

We looked at hemoglobin A1c (HbA1c) testing across 119,000 patients and 15 years of hospital records. We examined the patterns of HbA1c ordering before and after the publication of the 2002 American Diabetes Association guidelines for HbA1c testing. We conducted analyses to answer three questions. What are the patterns of HbA1c ordering? Do HbA1c orders follow the guidelines with respect to frequency of measurement? If not, how and why do they depart from the guidelines?

RESULTS

The raw number of HbA1c orderings has steadily increased over time, with a specific increase in low-measurement orderings (<6.5%). There is a change in ordering pattern following the 2002 guideline (p<0.001). However, by comparing ordering distributions, we found that the changes do not reflect the guidelines and rather exhibit a new practice of rapid-repeat testing. The rapid-retesting phenomenon does not follow the 2009 guidelines for diabetes diagnosis either, illustrated by a stratified HbA1c value analysis.

DISCUSSION

Results suggest HbA1c test overutilization, and contributing factors include lack of care coordination, unexpected values prompting retesting, and point-of-care tests followed by confirmatory laboratory tests.

CONCLUSIONS

We present a method of comparing ordering distributions in an EHR across time as a useful diagnostic approach for identifying and assessing the trend of inappropriate use over time.

The International Society of Pediatric and Adolescent Diabetes guidelines for management of diabetic ketoacidosis: Do the guidelines need to be modified?

The current version of the International Society of Pediatric and Adolescent Diabetes (ISPAD) guidelines for management of diabetic ketoacidosis (DKA) is largely based on the Lawson Wilkins Pediatric Endocrine Society/European Society of Pediatric Endocrinology (LWPES/ESPE) consensus statement on DKA in children and adolescents published in 2004. This article critically reviews and presents the most pertinent new data published in the past decade, which have implications for diagnosis and management. Four elements of the guidelines warrant modification: (i) The definition of DKA; (ii) insulin therapy; (iii) water and salt replacement; and (iv) blood ß-hydroxybutyrate measurements for the management of DKA.

Salivary proteins associated with hyperglycemia in diabetes: a proteomic analysis

Effective monitoring of glucose levels is necessary for patients to achieve greater control over their diabetes. However, only about a quarter of subjects with diabetes who requires close serum glucose monitoring, regularly check their serum glucose daily. One of the potential barriers to patient compliance is the blood sampling requirement. Saliva and its protein contents can be altered in subjects with diabetes, possibly due to changes in glycemic control. We propose here that salivary proteomes of subjects with diabetes may be different based on their glycemic control as reflected in A1C levels. A total of 153 subjects with type 1 or 2 diabetes were recruited. Subjects in each type of diabetes were divided into 5 groups based on their A1C levels; <7, 7-8, 8-9, 9-10, >10. To examine the global proteomic changes associated with A1C, the proteomic profiling of pooled saliva samples from each group was created using label-free quantitative proteomics. Similar proteomic analysis for individual subjects (N=4, for each group) were then applied to examine proteins that may be less abundant in pooled samples. Principle component analysis (PCA) and cluster analysis (p<0.01 and p<0.001) were used to define the proteomic differences. We, therefore, defined the salivary proteomic changes associated with A1C changes. This study demonstrates that differences exist between salivary proteomic profiles in subjects with diabetes based on the A1C levels.

Accuracy and robustness of dynamical tracking of average glycemia (A1c) to provide real-time estimation of hemoglobin A1c using routine self-monitored blood glucose data

BACKGROUND

Laboratory hemoglobin A1c (HbA1c) assays are typically done only every few months. However, self-monitored blood glucose (SMBG) readings offer the possibility for real-time estimation of HbA1c. We present a new dynamical method tracking changes in average glycemia to provide real-time estimation of A1c (eA1c).

MATERIALS AND METHODS

A new two-step algorithm was constructed that includes: (1) tracking fasting glycemia to compute base eA1c updated with every fasting SMBG data point and (2) calibration of the base eA1c trace with monthly seven-point SMBG profiles to capture the principal components of blood glucose variability and produce eA1c. A training data set (n=379 subjects) was used to estimate model parameters. The model was then fixed and applied to an independent test data set (n=375 subjects). Accuracy was evaluated in the test data set by computing mean absolute deviation (MAD) and mean absolute relative deviation (MARD) of eA1c from reference HbA1c, as well as eA1c-HbA1c correlation.

RESULTS

MAD was 0.50, MARD was 6.7%, and correlation between eA1c and reference HbA1c was r=0.76. Using an HbA1c error grid plot, 77.5% of all eA1c fell within 10% from reference HbA1c, and 97.9% fell within 20% from reference.

CONCLUSIONS

A dynamical estimation model was developed that achieved accurate tracking of average glycemia over time. The model is capable of working with infrequent SMBG data typical for type 2 diabetes, thereby providing a new tool for HbA1c estimation at the patient level. The computational demands of the procedure are low; thus it is readily implementable into home SMBG meters. Real-time HbA1c estimation could increase patients' motivation to improve diabetes control.

Can hemoglobin A1c in early pregnancy predict adverse pregnancy outcomes in diabetic patients?

OBJECTIVE

To examine the association of elevated early pregnancy hemoglobin A1c (HbA1c) levels with adverse pregnancy outcomes in women with preexisting diabetes mellitus.

STUDY DESIGN

Retrospective cohort study of 330 women with preexisting diabetes enrolled in a Diabetes in Pregnancy Program at an academic institution between 2003 and 2011 who had an early HbA1c determination. The frequencies of composite maternal adverse pregnancy outcomes (birth at<37 weeks, preeclampsia, and medically indicated birth <39 weeks), and composite fetal adverse pregnancy outcomes [shoulder dystocia, Apgar scores<7 at 5 minutes, small for gestational age (SGA), large for gestational age (LGA), and stillbirth] were compared between HbA1c categories (<6.5, 6.5-7.4, 7.5-8.4 and ≥ 8.5%).

RESULTS

There was no statistically significant difference between composite adverse maternal pregnancy outcomes and composite adverse fetal pregnancy outcomes as well as other individual outcomes between different HbA1c categories. Of the vaginally delivered women in our cohort, the 37 patients with HbA1c levels of ≥ 8.5% had a significantly higher frequency of fetal shoulder dystocia than the 62 with HbA1c levels of < 8.5% (24.2 vs. 1.6%, P = 0.002). Neonates of patients with HbA1c ≥ 8.5% were more likely to have low five minute Apgar scores than neonates of patients with HbA1c < 8.5%, but this was of borderline statistical significance (7.4% vs. 0.5%, P = 0.05).

CONCLUSION

In patients with preexisting diabetes mellitus, HbA1c levels of ≥ 8.5% during early pregnancy are not useful in predicting most adverse outcomes, although there may be an increased risk for shoulder dystocia.

Treat-to-target trials in diabetes

Treat-to-target is a therapeutic concept that considers well defined and specific physiologic targets as aims in controlling the pathophysiology of the disease. It has been widely used in diseases that pathophysiology includes, chronic metabolic and physiological disturbances, namely rheumatic conditions, vascular medicine and diabetes. In diabetes, the availability of "gold-standard" quantitative measures like fasting plasma glucose and glycated hemoglobin make the application of treat-to-target trials especially pertinent. Treatment modalities which have used single therapeutic agents or combinations or in combination with a variety of titration algorithms and implementation protocols have broadened our understanding of diabetes management with specific reference to insulin initiation and maintenance. Treat-to-target trials have been used to investigate a wide variety of questions including efficacy, safety, effect of treatment on comorbidities and patient satisfaction, ideal mechanisms to implement insulin initiation etc. A more generalized acceptance and implementation of treat-to-target trials may finally revolutionize diabetes management by combining aspects of individual care with standard treatment protocols.

The relationship between BMI and glycated albumin to glycated hemoglobin (GA/A1c) ratio according to glucose tolerance status

Glycated albumin to glycated hemoglobin (GA/A1c) ratio is known to be inversely related with body mass index (BMI) and insulin secretory capacity. However, the reasons for this association remain unknown. We aimed to investigate whether BMI directly or indirectly influences GA/A1c by exerting effects on insulin secretion or resistance and to confirm whether these associations differ according to glucose tolerance status. We analyzed a total of 807 subjects [242 drug-naïve type 2 diabetes (T2D), 378 prediabetes, and 187 normal glucose tolerance (NGT)]. To assess the direct and indirect effects of BMI on GA/A1c ratio, structural equation modeling (SEM) was performed. GA/A1c ratio was set as a dependent variable, BMI was used as the independent variable, and homeostasis model assessment-pancreatic beta-cell function (HOMA-β), homeostasis model assessment-insulin resistance (HOMA-IR), glucose level were used as mediator variables. The estimates of a direct effect of BMI on GA/A1c to be the strongest in NGT and weakest in T2D (−0.375 in NGT, −0.244 in prediabetes, and −0.189 in T2D). Conversely, the indirect effect of BMI on GA/A1c exerted through HOMA-β and HOMA-IR was not statistically significant in NGT group, but significant in prediabetes and T2D groups (0.089 in prediabetes, −0.003 in T2D). It was found that HOMA-β or HOMA-IR indirectly influences GA/A1c in T2D and prediabetes group through affecting fasting and postprandial glucose level. The relationship between GA/A1c and BMI is due to the direct effect of BMI on GA/A1c in NGT group, while in T2D and prediabetes groups, this association is mostly a result of BMI influencing blood glucose through insulin resistance or secretion.

Pitfalls in hemoglobin A1c measurement: when results may be misleading

Since the beginning of clinical use in the 1970s, hemoglobin A1c (A1c) has become the standard tool for monitoring glycemic control in patients with diabetes. The role of the A1c test was broadened in 2010, when the American Diabetes Association added A1c as a diagnostic criterion for diabetes. Because of hemoglobin A1c's integral role in diagnosis and treatment, it is important to recognize clinical scenarios and interfering factors that yield false results. The purpose of this review is to describe the A1c measurement, outline clinical scenarios or factors that may yield false results, and describe alternative laboratory biomarkers.

Beyond HbA1c and glucose: the role of nontraditional glycemic markers in diabetes diagnosis, prognosis, and management

Fasting glucose and hemoglobin A1c (HbA1c) are the standard measures for diagnosis and monitoring of diabetes. There has been recent interest in nontraditional markers of hyperglycemia, including fructosamine, glycated albumin, and 1,5-anhydroglucitol (1,5-AG), as alternatives or adjuncts to standard measures. There is a growing literature linking these nontraditional markers with microvascular and macrovascular complications. Fructosamine and glycated albumin have also been shown to improve identification of persons with diabetes. However, long-term prospective studies with clinical outcomes are lacking. Some modern laboratory assays for fructosamine, glycated albumin, and 1,5-AG have excellent performance. Expanded use of these tests has the potential to improve diabetes care as these measures may overcome limitations of HbA1c in certain patients, complement traditional measures by providing additional information on shorter-term glycemic control, and improve risk stratification for diabetes and its complications. Nonetheless, studies are needed to demonstrate if their routine use will benefit patients and improve outcomes.

Elevated hemoglobin A1c levels are associated with worse survival in advanced pancreatic cancer patients with diabetes

Background/Aims

Pre-existing diabetes mellitus (DM) has been identified as an adverse prognostic variable associated with increased mortality in various cancers. Although DM and hyperglycemia are considered risk factors for pancreatic cancer (PC), antidiabetic treatments for patients with advanced PC have been overlooked. This study aimed to evaluate the impact of hemoglobin A1c (HbA1c) levels on PC survival.

Methods

We retrospectively reviewed the medical records of first-diagnosed patients with advanced PC who were admitted to Konkuk University Medical Center from 2005 to 2011.

Results

A total of 127 patients were enrolled, and there were 111 deaths (87.4%) within the 7-year observational period. The most common etiology was disease progression (n=108). DM before PC diagnosis was observed in 65 patients (51.1%), including 28 patients with new-onset DM. The overall median survival times in patients with and without DM were 198 and 263 days, respectively (p=0.091). Survival time according to HbA1c was significantly different between the <7.0% and ≥7.0% groups (362 and 144 days, respectively; p=0.038). In the HbA1c ≥7.0% group, the median overall survival time was 273 days for the metformin group and 145 days for the nonmetformin oral agent group; however, there was no significant difference between the two groups (p=0.058).

Conclusions

A high HbA1c level may be associated with worse survival in patients with advanced PC with DM. Antidiabetic treatment, metformin in particular, was associated with an improved outcome.

Impact of HbA1c criterion on the definition of glycemic component of the metabolic syndrome: the China health and nutrition survey 2009

BACKGROUND

In 2009, a unified definition of metabolic syndrome (MetS) was proposed, of which, the glycemic component is defined on the basis of fasting plasma glucose (FPG) level. Recently, the American Diabetes Association (ADA) recommended the use of glycated hemoglobin (HbA1c) as an alternative to FPG to define prediabetes. Hence, we aim to compare the performance of HbA1c and FPG in the definition of glycemic component of the MetS among Chinese adults.

METHODS

We conducted a cross-sectional analysis of 7641 Chinese participants aged ≥18 years using data from the China Health and Nutrition Survey 2009. MetS was defined according to the consensus criteria in 2009. We compared the use of HbA1c versus FPG in the definition of the glycemic component of MetS. Increased HbA1c value was defined following the criterion of HbA1c cut-off point of ≥5.7% recommended by the ADA.

RESULTS

Overall, 1136 (14.9%) had MetS according to FPG ≥ 5.6 mmol/l, and 1640 (21.5%) had MetS according to HbA1c ≥ 5.7%. Compared with individuals with FPG-based diagnosis of MetS, individuals with HbA1c-based diagnosis of MetS were older, had higher levels of LDL-C, magnesium, and transferrin, and lower levels of uric acid. Of those found to have MetS according to either FPG or HbA1c (n = 2008), overlap between HbA1c- and FPG-based diagnosis of MetS was limited (n = 768, 38.2%). The overlap index regarding MetS diagnosed by FPG or HbA1c persisted low in each evaluated subgroup (≤ 50.0%).

CONCLUSIONS

We note limited overlap and poor agreement between FPG- and HbA1c-based diagnosis of MetS. Screening MetS through introduction of HbA1c in addition to FPG could contribute to identification of more people with MetS.

Influence of smoking and diet on glycated haemoglobin and 'pre-diabetes' categorisation: a cross-sectional analysis

BACKGROUND

The new HbA1c criteria for diagnosis of pre-diabetes have been criticised for misdiagnosis. It is possible that some elevation of HbA1c is not driven by hyperglycaemia. This study assesses associations of HbA1c, commonly assumed to relate solely to glucose concentration, with (i) smoking, a major source of reactive oxygen species (ROS) and (ii) fruit & vegetables consumption associated with improved redox status.

METHODS

One-way ANOVA, Chi-squared and multivariate linear regressions, adjusted for all known confounders were used to explore associations of HbA1c with self-reported smoking status and fruit & vegetables consumptions in the Scottish Health Surveys 2003-2010, among individuals without known diabetes and HbA1c < 6.5%.

RESULTS

Compared to non-smokers (n = 2831), smokers (n = 1457) were younger, consumed less fruit & vegetables, had lower physical activity levels, lower BMI, higher HbA1c and CRP (p < 0.05). HbA1c was higher in smokers by 0.25 SDs (0.08%), and 0.38 SDs higher (0.14%) in heavy smokers (>20 cigarettes/day) than non-smokers (p < 0.001 both). Smokers were twice as likely to have HbA1c in the 'pre-diabetic' range (5.7-6.4%) (p < 0.001, adj.model). Pre-diabetes and low grade inflammation did not affect the associations. For every extra 80 g vegetable portion consumed, HbA1c was 0.03 SDs (0.01%) lower (p = 0.02), but fruit consumption did not impact on HbA1c, within the low range of consumptions in this population.

CONCLUSION

This study adds evidence to relate smoking (an oxidative stress proxy) with protein glycation in normoglycaemic subjects, with implications for individuals exposed to ROS and for epidemiological interpretation of HbA1c.

Comparison of the performance of HbA1c and fasting plasma glucose in identifying dysglycaemic status in Chinese high-risk subjects

The aim of the present study was to compare the performance of HbA1c and fasting plasma glucose (FPG) in identifying dysglycaemic status among Chinese participants. Fasting plasma glucose and HbA1c were measured in 2318 subjects with at least one risk factor for diabetes but without being previously diagnosed with diabetes. Using HbA1c to diagnose diabetes resulted in the same classification as FPG for 90.5% of the study participants, with 21.0% (n = 487) classified as having diabetes by both FPG and HbA1c and 69.5% (n = 1610) classified as not having diabetes by both FPG and HbA1c. The kappa (κ) coefficient of the FPG criterion with the HbA1c criterion for diabetes was 0.75 (95% confidence interval (CI) 0.72-0.78). The overlap index regarding diabetes diagnosed by FPG or HbA1c was 68.8%. Of 1610 subjects with FPG < 126 mg/dL and HbA1c < 6.5%, 220 (13.7%) had FPG ≥ 100 mg/dL and HbA1c < 5.7%, whereas 277 (17.2%) had FPG < 100 mg/dL and HbA1c ≥ 5.7%. The κ coefficient of the FPG criterion with the HbA1c criterion for prediabetes was 0.30 (95% CI 0.25-0.35). The overlap index between subjects diagnosed as having prediabetes by FPG of 100-125 mg/dL (impaired fasting glucose (IFG)) or HbA1c of 5.7-6.4% (increased HbA1c (IGH)) was 35.9%. The HbA1c criterion demonstrates reasonable concordance with the FPG criterion for diabetes. Hence, HbA1c and FPG can be used for the diagnosis of diabetes. However, the IGH shows limited overlap with IFG for prediabetes. Introduction of the IGH criterion in addition to IFG for the screening of prediabetes could lead to the identification of more people with this condition.

The use of a CoolSense device to lower pain sensation during finger pricking while measuring blood glucose in diabetes patients--a randomized placebo

BACKGROUND

Patients with type 1 diabetes and a significant portion of patients with type 2 diabetes must use subcutaneous insulin injections, in order to maintain normoglycemia and to prevent immediate and long-term complications. For these patients, testing blood glucose levels more frequently is necessary to safely achieve glycated hemoglobin targets. In the current study, the effects of a CoolSense™ device (CoolSense Medical Ltd., Tel Aviv, Israel) were examined in relieving pain caused by needle-pricking for glucose measurements in adult patients with diabetes.

SUBJECTS AND METHODS

One hundred seventy-seven patients assessed the severity of pain they experienced during needle-pricking. The patients were randomly divided into an experimental group or a control group that used either a cooled CoolSense instrument or a non-cooled device, respectively. Participants were asked to rank the severity of their pain by a questionnaire developed for this study. Blood glucose levels were monitored as a control.

RESULTS

The majority of participants (58.3-71.7%; P<0.001) reported significant ache during measurements, the desire for an instrument that relieves pain, and its negative influence on their quality of life. Significant differences were indicated in pain perception between the experimental group and the control group that served as placebo, with no differences in blood glucose measurements in the groups.

CONCLUSIONS

The CoolSense instrument significantly reduces subjective pain felt by patients and can therefore serve as an additional tool for clinicians to help ease the needle-pricking pain. Future study is needed in order to provide information regarding the practical use of the instrument and its effect on hyper- and hypoglycemia.

Comparing patient-generated blood glucose diary records with meter memory in diabetes: a systematic review

AIMS

To synthesize evidence relating to comparisons between patient-generated blood glucose records and meter memory in diabetes and to identify any predictors of agreement.

METHODS

A systematic literature search was performed to identify articles comparing meter and diary records in those unaware of this assessment.

RESULTS

Eleven observational studies, covering patients with Type 1, Type 2 and gestational diabetes were included spanning 1984-2009. Failure to record blood glucose measurements in the diary was the most extensive 'error', but addition of values, which were not measured, was a greater cause for concern. When present to a high degree, 'errors' lead to decreased variability in diary records compared with meter records. Allowing for a minimal amount of disagreement, just over 50% of adult diaries can be considered as 'accurate/reliable'. Disagreements were most extensive in teenagers and young adults, but the pregnant populations were only slightly better. Agreement was not related to sex, number of insulin injections or duration of monitoring. Those who were younger were more likely to have 'errors', while those who monitored more frequently had more 'accurate' diaries.

CONCLUSIONS

The lack of meter-diary agreement suggests that the real reason for monitoring is not understood by many patients, raising issues about motivation, perceived need to impress healthcare providers and denial of poor control. Considering that diaries are used to inform decisions about therapy when HbA1c is raised or in pregnancy, when HbA1c is not suitable, there is significant cause for concern in relation to their clinical utility.

Evaluation of turbidimetric inhibition immunoassay (TINIA) and HPLC methods for glycated haemoglobin determination

BACKGROUND

Various factors may affect the accuracy of hemoglobin (Hb) A1c measurements that are widely used to monitor glycemic control in diabetic patients. This study was aimed to compare the values of HbA1c obtained by two different methods, Roche Tina-quant second and thirdgeneration HbA1c assays based on the turbidimetric inhibition immunoassay (TINIA), and high-performance liquid chromatography (HPLC) cation-exchange method used by Arkray Adams HA-8160 analyzer.

METHODS

Measurements of HbA1c were carried out in blood samples from 2,917 patients using above-mentioned methods. Linear regression was used for the correlation analysis and linear equations. Bland-Altman plots were performed from method comparison data using MedCalc statistical software.

RESULTS

For the low control, the second generation Tina-quant assay had within-run and between-run CVs 0.8% and 0.9%; for the high control within-run and between-run CVs were 1% and 0.96%, respectively. HPLC method for the low control had within-run CV 1% and between-run CV 1.3%; for the high control within-run CV was 0.6% and between-run CV was 0.9%.

CONCLUSION

There was a good concordance between the results of TINIA and HPLC methods (y = 1.091x - 0.363; r(2) = 0.96).

Blood β-hydroxybutyrate vs. urine acetoacetate testing for the prevention and management of ketoacidosis in Type 1 diabetes: a systematic review

AIM

Diabetic ketoacidosis is a life-threatening complication of Type 1 diabetes. Blood β-hydroxybutyrate testing is now widely available as an alternative to urine acetoacetate testing for detecting ketosis. The aim of this study was to review the effectiveness of capillary or serum β-hydroxybutyrate compared with urine acetoacetate testing in prevention and management of diabetic ketoacidosis.

METHODS

MEDLINE, EMBASE, EBM Reviews, The Cochrane Library and CINAHL (until April 2012, no language restrictions, studies in humans) were searched for experimental and observational studies comparing the effectiveness of blood β-hydroxybutyrate and urine acetoacetate testing. Outcomes examined were prevention of diabetic ketoacidosis, time to recovery from diabetic ketoacidosis, healthcare costs and patient or caregiver satisfaction. Additional sources included reference lists, conference proceedings and contact with experts in the field.

RESULTS

Four studies (two randomized controlled trials and two cohort studies) met eligibility criteria, including 299 participants across 11 centres. Risk of bias was low to moderate. Blood ketone testing compared with urine testing was associated with reduced frequency of hospitalization (one study), reduced time to recovery from diabetic ketoacidosis (three studies), cost benefits (one study) and greater satisfaction (one study, intervention group only). No study assessed prevention of diabetic ketoacidosis. Meta-analysis could not be performed because of heterogeneity in study design and published data.

CONCLUSIONS

There is evidence suggesting that blood β-hydroxybutyrate testing is more effective than urine acetoacetate testing in reducing emergency department assessment, hospitalization and time to recovery from diabetic ketoacidosis, as well as potentially lowering healthcare expenditure. Further research in both young people and adults is needed.

The use of 1.5-anhydroglucitol for monitoring glycemic control in islet transplant recipients

We evaluated whether 1,5-anhydroglucitol (1,5-AG) (GlycoMark(®)), a test for measuring postprandial glucose and glucose variability, could be a tool for assessing short-term glycemic control in islet cell transplant (ICT) subjects. Data of 21 subjects, with type 1 DM and allogenic islet transplantation, who had concomitant fructosamine, HbA1c, 1,5-AG (n = 85 samples), and capillary glucose self-monitoring measurements (n = 2,979) were analyzed retrospectively at different time points after ICT. A significant negative association was observed between 1,5-AG and HbA1c (p = 0.02), but not with fructosamine. When HbA1c was divided in quartiles as <5.6, 5.6-5.9, 5.9-6.2, and >6.2, a decrease of an estimated 0.70 ± 0.30 µg/ml in 1,5-AG was associated with each quartile of increase in HbA1c (p < 0.0001). There was a significant decline of 1.64 ± 0.3mg/dl in postprandial glucose values for each 1 unit increase in 1,5-AG (p < 0.0001). For those with HbA1c ≥ 6.0% when 1,5-AG was ≥8.15 µg/ml, the mean estimated glucose level was 103.71 ± 3.66 mg/dl, whereas it was 132.12 ± 3.71 mg/dl when 1,5-AG was <8.15 µg/ml. The glucose variability (Glumax - Glumin) in subjects with 1,5-AG <8.15 µg/ml was 46.23 mg/dl greater than the subjects with 1,5-AG ≥8.15 µg/ml (HbA1c ≥ 6.0%). There was no significant association between GlycoMark and glucose variability where HbA1c < 6%. 1,5-AG significantly associated with postprandial glucose levels and glucose variability in ICT recipients with near-normal HbA1c (6.0-6.5%) levels. These findings suggest that 1,5-AG can be used to differentiate those ICT subjects with higher glucose variability despite having near-normal HbA1c. However, prospective studies are needed to evaluate the association between GlycoMark levels and the parameters of graft dysfunction/failure.

Plasma fructosamine concentrations in horses with pituitary pars intermedia dysfunction with and without laminitis

REASONS FOR PERFORMING STUDY

Plasma fructosamine concentration ([fructosamine]) is believed to reflect medium term, average blood glucose concentration and in a previous study was higher in horses with active laminitis than in normal horses. Pituitary pars intermedia dysfunction (PPID) is associated with hyperglycaemia and laminitis.

OBJECTIVES

To test the hypotheses that: [fructosamine] is higher in PPID cases than normal animals; furthermore, that within cases of PPID [fructosamine] is higher in those with active laminitis than nonlaminitic cases and in cases that have been affected by active laminitis in the preceding year than those that have not.

STUDY DESIGN

Observational, case-control/cross-sectional study.

METHODS

[Fructosamine] was measured in cases of PPID (n = 46) and normal animals (n = 139). A normal range was calculated; values were compared between the 2 groups and within the PPID group, between cases with and without active laminitis and between cases that had and had not been affected by active laminitis in the preceding year.

RESULTS

In normal animals mean [fructosamine] was 248.7 μmol/l; the normal range (mean ± 2 s.d.) was 195.5-301.9 μmol/l. Plasma [fructosamine] was not higher in PPID cases than in normal animals. In PPID cases, [fructosamine] was significantly (P = 0.006) higher in cases with active laminitis (mean ± s.d. 261.2 ± 39.2 μmol/l) compared with those without active laminitis (234.5 ± 32.9 μmol/), but [fructosamine] was not higher in cases that had been affected by active laminitis in the preceding year than those that had not.

CONCLUSIONS

In horses affected by PPID, [fructosamine] is higher in cases with active laminitis than in cases without active laminitis.

POTENTIAL RELEVANCE

Clinical use of [fructosamine] is limited due to overlap with the normal range. Further studies into glucose and protein metabolism in cases of PPID are warranted.

Effects of green tea catechins with or without caffeine on glycemic control in adults: a meta-analysis of randomized controlled trials

BACKGROUND

The effect of green tea catechins (GTCs) with or without caffeine on glycemic control is controversial.

OBJECTIVE

We aimed to identify and quantify the effects of GTCs or GTC-caffeine mixtures on glucose metabolism in adults.

DESIGN

A comprehensive literature search was conducted to identify relevant trials of GTCs with or without caffeine on markers of glycemic control [fasting blood glucose (FBG), fasting blood insulin (FBI), glycated hemoglobin (Hb A1c), and homeostatic model assessment of insulin resistance (HOMA-IR)]. Weighted mean differences were calculated for net changes by using fixed-effects models. Prespecified subgroup analyses were performed to explore the influence of covariates on net changes in FBG and FBI concentrations.

RESULTS

Twenty-two eligible randomized controlled trials with 1584 subjects were identified. Pooled analyses showed that FBG (-1.48 mg/dL; 95% CI: -2.57, -0.40 mg/dL) decreased significantly with GTCs with or without caffeine, whereas FBI (0.04 μU/mL; 95% CI: -0.36, 0.45 μU/mL), Hb A1c (-0.04%; 95% CI: -0.15, 0.08%), and HOMA-IR (-0.05; 95% CI: -0.37, 0.26) did not. Subgroup analyses indicated that the glucose-lowering effect was apparent when the duration of follow-up was over a median of 12 wk. Overall, no significant heterogeneity was detected for FBG, FBI, Hb A1c, or HOMA-IR.

CONCLUSIONS

The meta-analysis showed that the administration of GTCs with or without caffeine resulted in a significant reduction in FBG. The limited data available on GTCs did not support a positive effect on FBI, Hb A1c, or HOMA-IR. Thus, more large and well-designed trials are needed in the future. This trial was registered at http://www.crd.york.ac.uk/prospero as CRD42012002139.