Serum 1,5-anhydroglucitol levels slightly increase rather than decrease after a glucose load in subjects with different glucose tolerance status

Recent Developments in Biomarkers for Diagnosis and Screening of Type 2 Diabetes Mellitus

PURPOSE OF REVIEW

Diabetes mellitus is a complex, chronic illness characterized by elevated blood glucose levels that occurs when there is cellular resistance to insulin action, pancreatic β-cells do not produce sufficient insulin, or both. Diabetes prevalence has greatly increased in recent decades; consequently, it is considered one of the fastest-growing public health emergencies globally. Poor blood glucose control can result in long-term micro- and macrovascular complications such as nephropathy, retinopathy, neuropathy, and cardiovascular disease. Individuals with diabetes require continuous medical care, including pharmacological intervention as well as lifestyle and dietary changes.

RECENT FINDINGS

The most common form of diabetes mellitus, type 2 diabetes (T2DM), represents approximately 90% of all cases worldwide. T2DM occurs more often in middle-aged and elderly adults, and its cause is multifactorial. However, its incidence has increased in children and young adults due to obesity, sedentary lifestyle, and inadequate nutrition. This high incidence is also accompanied by an estimated underdiagnosis prevalence of more than 50% worldwide. Implementing successful and cost-effective strategies for systematic screening of diabetes mellitus is imperative to ensure early detection, lowering patients' risk of developing life-threatening disease complications. Therefore, identifying new biomarkers and assay methods for diabetes mellitus to develop robust, non-invasive, painless, highly-sensitive, and precise screening techniques is essential. This review focuses on the recent development of new clinically validated and novel biomarkers as well as the methods for their determination that represent cost-effective alternatives for screening and early diagnosis of T2DM.

Saliva 1,5-anhydroglucitol is associated with early-phase insulin secretion in Chinese patients with type 2 diabetes

INTRODUCTION

Saliva collection is a non-invasive test and is convenient. 1,5-anhydroglucitol (1,5-AG) is a new indicator reflecting short-term blood glucose levels. This study aimed to explore the relationship between saliva 1,5-AG and insulin secretion function and insulin sensitivity.

RESEARCH DESIGN AND METHODS

Adult patients with type 2 diabetes who were hospitalized were enrolled. Based on blood glucose and C-peptide, homeostasis model assessment 2 for β cell secretion function, C-peptidogenic index (CGI), △2-hour C-peptide (2hCP)/△2-hour postprandial glucose (2hPG), ratio of 0-30 min area under the curve for C-peptide and area under the curve for glucose (AUC_CP30/AUC_PG30), and AUC_2hCP/AUC_2hPG were calculated to evaluate insulin secretion function, while indicators such as homeostasis model assessment 2 for insulin resistance were used to assess insulin sensitivity.

RESULTS

We included 284 subjects (178 men and 106 women) with type 2 diabetes aged 20-70 years. The saliva 1,5-AG level was 0.133 (0.089-0.204) µg/mL. Spearman's correlation analysis revealed a significantly negative correlation between saliva 1,5-AG and 0, 30, and 120 min blood glucose, glycated hemoglobin A_1c, and glycated albumin (all p<0.05), and a significantly positive association between saliva 1,5-AG and CGI (r=0.171, p=0.004) and AUC _CP30 /AUC _PG30 (r=0.174, p=0.003). The above correlations still existed after adjusting for age, sex, body mass index, and diabetes duration. In multiple linear regression, saliva 1,5-AG was an independent factor of CGI (standardized β=0.135, p=0.015) and AUC _CP30 /AUC _PG30 (standardized β=0.110, p=0.020).

CONCLUSIONS

Saliva 1,5-AG was related to CGI and AUC_CP30/AUC_PG30 in patients with type 2 diabetes.

TRIAL REGISTRATION NUMBER

ChiCTR-SOC-17011356.

Diabetes Screening: Detection and Application of Saliva 1,5-Anhydroglucitol by Liquid Chromatography-Mass Spectrometry

CONTEXT

Unlike other commonly used invasive blood glucose-monitoring methods, saliva detection prevents patients from suffering physical uneasiness. However, there are few studies on saliva 1,5-anhydroglucitol (1,5-AG) in patients with diabetes mellitus (DM).

OBJECTIVE

This study aimed to evaluate the effectiveness of saliva 1,5-AG in diabetes screening in a Chinese population.

DESIGN AND PARTICIPANTS

This was a population-based cross-sectional study. A total of 641 subjects without a valid diabetic history were recruited from September 2018 to June 2019. Saliva 1,5-AG was measured with liquid chromatography-mass spectrometry.

MAIN OUTCOME MEASURES

DM was defined per American Diabetes Association criteria. The efficiency of saliva 1,5-AG for diabetes screening was analyzed by receiver operating characteristic curves, and the optimal cutoff point was determined according to the Youden index.

RESULTS

Saliva 1,5-AG levels in subjects with DM were lower than those in subjects who did not have DM (both P < .05). Saliva 1,5-AG was positively correlated with serum 1,5-AG and negatively correlated with blood glucose and glycated hemoglobin (HbA1c) (all P < .05). The optimal cutoff points of saliva 1,5-AG0 and 1,5-AG120 for diabetes screening were 0.436 μg/mL (sensitivity: 63.58%, specificity: 60.61%) and 0.438 μg/mL (sensitivity: 62.25%, specificity: 60.41%), respectively. Fasting plasma glucose (FPG) combined with fasting saliva 1,5-AG reduced the proportion of people who required an oral glucose tolerance test by 47.22% compared with FPG alone.

CONCLUSION

Saliva 1,5-AG combined with FPG or HbA1c improved the efficiency of diabetes screening. Saliva 1,5-AG is robust in nonfasting measurements and a noninvasive and convenient tool for diabetes screening.

Potential Markers of Dietary Glycemic Exposures for Sustained Dietary Interventions in Populations without Diabetes

There is considerable interest in dietary and other approaches to maintaining blood glucose concentrations within the normal range and minimizing exposure to postprandial hyperglycemic excursions. The accepted marker to evaluate the sustained maintenance of normal blood glucose concentrations is glycated hemoglobin A1c (HbA1c). However, although this is used in clinical practice to monitor glycemic control in patients with diabetes, it has a number of drawbacks as a marker of efficacy of dietary interventions that might beneficially affect glycemic control in people without diabetes. Other markers that reflect shorter-term glycemic exposures have been studied and proposed, but consensus on the use and relevance of these markers is lacking. We have carried out a systematic search for studies that have tested the responsiveness of 6 possible alternatives to HbA1c as markers of sustained variation in glycemic exposures and thus their potential applicability for use in dietary intervention trials in subjects without diabetes: 1,5-anhydroglucitol (1,5-AG), dicarbonyl stress, fructosamine, glycated albumin (GA), advanced glycated end products (AGEs), and metabolomic profiles. The results suggest that GA may be the most promising for this purpose, but values may be confounded by effects of fat mass. 1,5-AG and fructosamine are probably not sensitive enough to the range of variation in glycemic exposures observed in healthy individuals. Use of measures based on dicarbonyls, AGEs, or metabolomic profiles would require further research into possible specific molecular species of interest. At present, none of the markers considered here is sufficiently validated and sensitive for routine use in substantiating the effects of sustained variation in dietary glycemic exposures in people without diabetes.

1,5-Anhydroglucitol × glycated hemoglobin A1c/100 as a potential biomarker for islet β-cell function among patients with type 2 diabetes

AIMS

This study aimed to explore the level of and changes in the 1,5-anhydroglucitol × glycated hemoglobin A_1c/100 (AH index, AHI) associated with different glucose metabolism statuses and to evaluate the islet function and insulin sensitivity of patients with type 2 diabetes (T2DM) with different AHI levels.

METHODS

Of the 3562 subjects enrolled in this study, 1697 had T2DM. The disposition index (DI) was the product of islet secretion function and insulin sensitivity-related indexes.

RESULTS

The mean AHI level was 1.0 (0.7-1.3) in the general population, while the mean AHI level in the T2DM group was 0.8 (0.5-1.2), which was significantly lower than that in the impaired glucose regulation and normal glucose tolerance group (both 1.2 (0.9-1.5), both P < 0.01). We further divided patients with T2DM into four subgroups according to the quartile of AHI. The results showed that with the increase in AHI level, the homeostasis model assessment of insulin resistance (HOMA-IR) decreased, while HOMA-β, insulin generation index, insulin sensitivity index, and DI increased (all P_{for trend} < 0.01). Multivariate logistic regression showed that the odds ratios for a low DI for increasing levels of AHI were 1.00, 0.22 (0.16-0.29), 0.16 (0.11-0.22), and 0.09 (0.06-0.13), showing a decreasing trend (P_{for trend} < 0.05).

CONCLUSION

The AHI could reflect the variation in glycemic disorder and the function of islet β cells. The lower the AHI, the worse the glycemic disorder, as well as the islet β-cell function.

Serum 1,5-Anhydroglucitol to Glycated Albumin Ratio Can Help Early Distinguish Fulminant Type 1 Diabetes Mellitus from Newly Onset Type 1A Diabetes Mellitus

BACKGROUND

Fulminant type 1 diabetes mellitus (FT1DM) onsets abruptly and usually occurs within 1 week after the onset of hyperglycemic symptoms. Glycated albumin (GA) and 1,5-anhydroglucitol (1,5-AG) are indicators that reflect short-term glucose levels. This study was aimed at investigating whether the 1,5-AG/GA index (AGI) is a suitable indicator for early FT1DM identification.

METHODS

A total of 226 subjects were enrolled, all with glycated hemoglobin A1c (HbA1c) < 8.7%. FT1DM was diagnosed based on the 2012 Japan Diabetes Society criteria.

RESULTS

The AGI level was 0.54 (0.17-1.36) in the whole group. It was lower in FT1DM patients (0.16 [0.10-0.25]). Among the participants whose HbA1c did not exceed 7.0%, the AGI of FT1DM decreased significantly compared to type 1A diabetes (T1ADM) and latent autoimmune diabetes in adults (LADA) patients (0.16 [0.12-0.26] vs. 0.46 [0.24-0.72] vs. 0.46 [0.24-0.72] P < 0.05). The receiver operating characteristic (ROC) curve showed that AGI can be used to distinguish FT1DM and T1ADM patients with HbA1c < 8.7%. Diagnosing FT1DM based on AGI ≤ 0.3 only can help narrow down suspected FT1DM by up to 26.87%. If we diagnosed FT1DM when AGI was ≤0.3 and HbA1c was ≤7.0%, the success rate further increased to 86.57%, among which 85.00% of FT1DM and 87.23% of T1ADM patients were successfully identified. Therefore, using the combination criteria of AGI and HbA1c would improve the differential diagnosis efficacy by 61.11% compared with the AGI criterion only.

CONCLUSION

AGI can help facilitate the early differential diagnosis of FT1DM and T1ADM when HbA1c < 8.7%, with an optimal cut-off point of 0.3.

Correlation of Serum 1,5-AG with Uric Acid in Type 2 Diabetes Mellitus with Different Renal Functions

AIM

Recent studies found that levels of serum uric acid (SUA) were positively associated with serum 1,5-anhydroglucitol (1,5-AG) in subjects with type 2 diabetes mellitus (T2DM). In the current study, we investigated the association between 1,5-AG and UA in T2DM patients with different renal functions.

METHODS

A total of 405 T2DM patients, 213 men and 192 women, participated in the study. Patients' clinical information was collected, and serum 1,5-AG, SUA, and other clinical characteristics were measured. Correlation analyses were carried out to analyze their correlation with serum 1,5-AG and SUA.

RESULTS

The male group showed higher levels of SUA than the female group (282.1 ± 91.2 and 244.7 ± 71.89 μmol/L, respectively, P < 0.01). Pearson's correlation coefficients determine that SUA was positively associated with 1,5-AG in both men (r = 0.213, P < 0.05) and women (r = 0.223, P < 0.05), and such relationship can be influenced by the renal function. The positive association still existed with moderate impaired renal function. Moreover, 1,5-AG had a negative association with haemoglobin A1c (HbA1c) in T2DM subjects with eGFR ≥ 30 mL/min/1.73 m² (P < 0.01).

CONCLUSION

The positive association between SUA and 1,5-AG still exists in T2DM with moderate renal failure. 1,5-AG can still reflect the glucose levels in patients with CKD stages 1-3.

Maternal glycemic parameters and adverse pregnancy outcomes among high-risk pregnant women

OBJECTIVE

We aimed to investigate the association between maternal glycemic parameters and adverse pregnancy outcomes among high-risk pregnant women.

RESEARCH DESIGN AND METHODS

A total of 1976 high-risk pregnant women were enrolled between 2015 and 2017. All participants received a 75 g oral glucose tolerance test during the 24-30 gestational weeks and complete birth and delivery information was collected. Adverse pregnancy outcomes were defined as premature birth, birth weight >90th percentile, primary cesarean section, and pre-eclampsia. Logistic regression models were used to assess the association between five maternal glycemic parameters during pregnancy (fasting glucose, 1-hour glucose, 2-hour glucose, HbA1c, and serum 1,5-anhydroglucitol (1,5-AG)) and adverse pregnancy outcomes.

RESULTS

Of 1976 participants, 498 were diagnosed with gestational diabetes. The multivariable-adjusted ORs of adverse pregnancy outcomes for each one unit increase (1 mmol/L, 1%, or 1 µg/mL) were 2.32 (95% CI 1.85 to 2.92) for fasting glucose, 1.07 (95% CI 1.01 to 1.15) for 1-hour glucose, 1.03 (95% CI 0.96 to 1.10) for 2-hour glucose, 1.77 (95% CI 1.34 to 2.33) for HbA1c, and 0.96 (95% CI 0.94 to 0.98) for 1,5-AG, respectively. When all five glycemic parameters were simultaneously entered into the multivariable-adjusted model, only fasting glucose was significantly associated with total and individual adverse pregnancy outcomes. Receiver operating characteristic curve showed that fasting glucose plus any one of other four glycemic parameters had significantly enhanced the sensitivity of detecting adverse pregnancy outcomes.

CONCLUSIONS

Fasting glucose at 24-30 gestational weeks was strongly associated with adverse pregnancy outcomes. Fasting glucose combined with one additional glycemic measurement showed non-inferiority indicating that post-load glycemic measurement was not necessary in detecting adverse pregnancy outcomes among high-risk pregnant women.

The metabolism and transport of 1,5-anhydroglucitol in cells

AIMS

Our previous studies demonstrated that serum 1,5-anhydroglucitol (1,5-AG) levels increased slightly rather than declined after an acute glucose load. Therefore, the current study aims at exploring the transport and metabolic characteristics of 1,5-AG, as well as the effect of glucose on 1,5-AG transport.

METHODS

K_m and V_max were determined to measure the affinity of glucose oxidase (GOD) and hexokinase (HK) for 1,5-AG and glucose. HepG2, C2C12, and primary mouse hepatocytes were incubated for 2 h with 1,5-AG at concentrations of 0, 80, and 160 μg/mL. Then, intracellular and extracellular concentrations of 1,5-AG were measured before and after washing with PBS to evaluate the transport and metabolic rates of 1,5-AG. In addition, the influence of an acute glucose load on the transport of 1,5-AG was studied.

RESULTS

The affinity of GOD and HK for 1,5-AG is 5 and 42.5% of that for glucose, respectively. Moreover, there is no de novo synthesis of 1,5-AG, and its metabolic rate is < 3%. After a 2 h incubation with additional 1,5-AG, the intracellular levels of 1,5-AG were 50-80% of extracellular levels. Moreover, intracellular 1,5-AG concentrations decreased rapidly and reached zero following the removal of 1,5-AG from the external medium. In addition, an acute glucose load can affect the dynamic balance of 1,5-AG, causing the intracellular 1,5-AG levels to decline significantly and the extracellular levels to increase slightly in HepG2 cells.

CONCLUSIONS

Unlike glucose, 1,5-AG is hard to be metabolized in vivo, and its transport is influenced by an acute glucose load in hepatocytes.

Serum 1,5-anhydroglucitol when used with fasting plasma glucose improves the efficiency of diabetes screening in a Chinese population

Serum 1,5-anhydroglucitol (1,5-AG) levels can not only accurately reflect the mean blood glucose over the previous 1–2 weeks in diabetic patients but also offers the advantage of representing postprandial glucose. To evaluate the clinical significance of 1,5-AG in diabetes detection, especially when used in combination with fasting plasma glucose (FPG), a total of 3098 participants at high risk for diabetes (1467 men, 1631 women) were enrolled. A total of 1471 (47.5%) participants were diagnosed with diabetes, and the mean 1,5-AG level in the diabetic group was significantly lower than that in non-diabetic group [12.5 (7.8–17.5) μg/mL vs. 20.5 (15.3–26.4) μg/mL, P < 0.001]. The optimal cut-off point was 15.9 μg/mL, for which the sensitivity, specificity, and area under the curve (AUC) were 69.2%, 72.3%, and 0.781, respectively. For the combination of FPG and 1,5-AG, the sensitivity, specificity, and AUC improved to 82.5%, 83.5%, and 0.912, respectively. This method helped 75.8% of the participants avoid an oral glucose tolerance test (OGTT), reducing the need to carry out the OGTT by 43.9% compared to the use of the FPG criterion only. In conclusion, the addition of FPG to serum 1,5-AG improves the efficiency of diabetes screening in the Chinese population.

Comparative Agreement Analysis of Differences in 1,5-Anhydroglucitol, Glycated Albumin, and Glycated Hemoglobin A1c Levels between Fasting and Postprandial States in Steamed Bread Meal Test

BACKGROUND

Our previous study indicated that serum 1,5-anhydroglucitol (1,5-AG) levels slightly increased after a glucose load; therefore, this study was conducted to explore short-term changes in 1,5-AG levels after a steamed bread meal test (SBMT) and compare the agreement of 1,5-AG, glycated albumin (GA), and glycated hemoglobin A1c (HbA1c) levels between fasting and postprandial states after an SBMT.

METHODS

104 participants were recruited and underwent a 100 g SBMT. Fasting, 30 min, and 120 min of 1,5-AG, GA, and HbA1c were measured.

RESULTS

Levels of 1,5-AG slightly increased from 30 to 120 min after an SBMT (P < 0.01), and HbA1c and GA levels showed stability at 30 and 120 min. The Passing-Bablok regression linear equation showed that postprandial 1,5-AG, GA, and HbA1c levels were well fitted (all P > 0.05), and Bland-Altman difference plot showed that 100% of data points for HbA1c₃₀ and HbA1c₁₂₀ fell within the limits of agreement; 94.2%, 96.2%, 95.2%, and 95.2% of data points for 1,5-AG₃₀, 1,5-AG₁₂₀, GA₃₀, and GA₁₂₀ fell within the limits of agreement, respectively.

CONCLUSION

Agreement analyses indicated good stability of 1,5-AG, GA, and HbA1c levels after the SBMT. HbA1c had an optimal stability, which was superior to that of GA or 1,5-AG.