Prediabetes and risk of diabetes and associated complications: impaired fasting glucose versus impaired glucose tolerance: does it matter?

Link between remnant cholesterol and the reversion to normoglycemia in Chinese adults with prediabetes: a 5-year cohort study

Despite the clear association between remnant cholesterol (RC)and diabetes risk, no study to date has examined the relationship between RC and reversal of prediabetes to normoglycemia. This retrospective cohort study included a total of 15,023 patients with prediabetes who underwent a physical examination between 2010 and 2016. The link between initial RC levels and the reversion from prediabetes to normoglycemia was analyzed using the Cox proportional-hazards regression model. Additionally, the study explored the possible relationship between RC and the probability of returning normoglycemia by applying Cox proportional hazards regression models with cubic spline functions. To address competing risks, a multivariate Cox regression analysis was undertaken, treating the onset of diabetes as a competing risk event for reversing prediabetes to normoglycemia. Additionally, the study incorporated extensive subgroup analyses alongside multiple sensitivity analyses, enhancing the reliability and robustness of the results. After adjusting for covariates, the findings indicated that RC was inversely associated with the likelihood of reverting to normoglycemia (per 5 mg/dL increase, HR = 0.918, 95% CI 0.909-0.927). The analysis also revealed a nonlinear relationship between RC and normoglycemia reversion, with an inflection point at 51.08 mg/dL. For RC values below this inflection point (RC < 50.08 mg/dL), the HR for the probability of returning to normoglycemia was 0.907 (95% CI 0.897-0.917 per 5 mg/dL). Additionally, the competing risks model demonstrated a negative relationship between RC and the reversal of prediabetes to normoglycemia (SHR = 0.92, 95% CI 0.91-0.93). Sensitivity analyses confirmed the robustness and stability of these results. This study demonstrated a negative and non-linear association between RC and the probability of reversion to normoglycemia in Chinese adults with prediabetes. By actively intervening to reduce RC levels, at least to below 51.08 mg/dL, further reduction of RC may significantly increase the probability of returning to normoglycemia from prediabetes.

Precision nutrition for targeting pathophysiology of cardiometabolic phenotypes

Obesity is a heterogenous disease accompanied by a broad spectrum of cardiometabolic risk profiles. Traditional paradigms for dietary weight management do not address biological heterogeneity between individuals and have catastrophically failed to combat the global pandemic of obesity-related diseases. Nutritional strategies that extend beyond basic weight management to instead target patient-specific pathophysiology are warranted. In this narrative review, we provide an overview of the tissue-level pathophysiological processes that drive patient heterogeneity to shape distinct cardiometabolic phenotypes in obesity. Specifically, we discuss how divergent physiology and postprandial phenotypes can reveal key metabolic defects within adipose, liver, or skeletal muscle, as well as the integrative involvement of the gut microbiome and the innate immune system. Finally, we highlight potential precision nutritional approaches to target these pathways and discuss recent translational evidence concerning the efficacy of such tailored dietary interventions for different obesity phenotypes, to optimise cardiometabolic benefits.

Prevalence and correlates of pre-diabetes in adults of mixed ethnicities in the South African population: A systematic review and meta-analysis

INTRODUCTION

Pre-diabetes is a metabolic condition characterised by moderate glycaemic dysregulation and is a frontline risk factor for multiple metabolic complications such as type 2 diabetes mellitus. To the best of our knowledge, this will be the first systematic review and meta-analysis focusing on generating a comprehensive pooling of studies reporting on pre-diabetes prevalence in South Africa. Therefore, the review's purpose will be to screen and select reports that can be used to synthesise and provide the best estimate prevalence of pre-diabetes and its associated correlates in the South African population.

METHODS AND ANALYSIS

To determine the prevalence and correlates of pre-diabetes in South Africa, we searched PubMed, Web of Science, Google scholar and African Journal online for published or unpublished studies reporting the prevalence of pre-diabetes in South Africa starting from the year 2000 to 2020. Studies were assessed for eligibility by checking if they met the inclusion criteria.

RESULTS & CONCLUSION

The total number of studies deemed eligible is 13 and from these studies, an overall prevalence of pre-diabetes was reported to be 15,56% in the South African population. Hypertension, obesity and sedentary lifestyle were the common correlates recorded for the population of interest. Therefore, the review highlights the disturbingly high prevalence of pre-diabetes in South Africa and necessitates further investigations into the possible genetics, biochemical and hormonal changes in pre-diabetes.

ETHICS AND DISSEMINATION

The review will not require ethics clearance because non-identifiable data will be used. The review outcomes will give insight into the current burden that pre-diabetes has in South Africa.

PROSPERO REGISTRATION NUMBER

CRD42020182430.

Does the Effect of a 3-Year Lifestyle Intervention on Body Weight and Cardiometabolic Health Differ by Prediabetes Metabolic Phenotype? A Post Hoc Analysis of the PREVIEW Study

OBJECTIVE

To examine whether the effect of a 3-year lifestyle intervention on body weight and cardiometabolic risk factors differs by prediabetes metabolic phenotype.

RESEARCH DESIGN AND METHODS

This post hoc analysis of the multicenter, randomized trial, PREVention of diabetes through lifestyle interventions and population studies In Europe and around the World (PREVIEW), included 1,510 participants with prediabetes (BMI ≥25 kg ⋅ m-2; defined using oral glucose tolerance tests). Of these, 58% had isolated impaired fasting glucose (iIFG), 6% had isolated impaired glucose tolerance (iIGT), and 36% had IFG+IGT; 73% had normal hemoglobin A1c (HbA1c; <39 mmol ⋅ mol-1) and 25% had intermediate HbA1c (39-47 mmol ⋅ mol-1). Participants underwent an 8-week diet-induced rapid weight loss, followed by a 148-week lifestyle-based weight maintenance intervention. Linear mixed models adjusted for intervention arm and other confounders were used.

RESULTS

In the available-case and complete-case analyses, participants with IFG+IGT had greater sustained weight loss after lifestyle intervention (adjusted mean at 156 weeks -3.5% [95% CI, -4.7%, -2.3%]) than those with iIFG (mean -2.5% [-3.6%, -1.3%]) relative to baseline (P = 0.011). Participants with IFG+IGT and iIFG had similar cardiometabolic benefits from the lifestyle intervention. The differences in cardiometabolic benefits between those with iIGT and IFG+IGT were minor or inconsistent in different analyses. Participants with normal versus intermediate HbA1c had similar weight loss over 3 years and minor differences in cardiometabolic benefits during weight loss, whereas those with normal HbA1c had greater improvements in fasting glucose, 2-h glucose (adjusted between-group difference at 156 weeks -0.54 mmol ⋅ L-1 [95% CI -0.70, -0.39], P < 0.001), and triglycerides (difference -0.07 mmol ⋅ L-1 [-0.11, -0.03], P < 0.001) during the lifestyle intervention.

CONCLUSIONS

Individuals with iIFG and IFG+IGT had similar improvements in cardiometabolic health from a lifestyle intervention. Those with normal HbA1c had greater improvements than those with intermediate HbA1c.

Lonicerae Japonicae Flos extract and chlorogenic acid attenuates high-fat-diet- induced prediabetes via CTRPs-AdipoRs-AMPK/PPARα axes

Prediabetes is considered an important reversible checkpoint in T2DM development, which can be delayed and prevented by early interventions. Lonicerae Japonicae Flos (LJF), an edible-medicinal herb, is rich in chlorogenic acid (CGA, 5-O-caffeoylquinic acid) and exerts anti-diabetes effects, but its role in prediabetes remains unclear. The purpose of this study was to explore the effects of LJF extract and CGA on rat with prediabetes. Sprague-Dawley rats were given high-fat diet (HFD) to induce prediabetes, and glycolipid metabolism parameters and molecular mechanisms were evaluated. LJF (the LJF extract treatment group) and CGA (the pure CGA treatment group) significantly attenuated HFD-induced prediabetes with impaired glucose tolerance and dyslipidemia, but their mechanisms of action are not exactly the same. Specifically, LJF prioritizes increasing protective lipid species [such as increasing blood polyunsaturated fatty acids (PUFA)-containing diacylglycerol (DAG) species, high-density lipoprotein-cholesterol (HDL-C)], whereas CGA prioritizes reducing detrimental lipid species [such as saturated fatty acid-containing DAG species, low-density lipoprotein-cholesterol (LDL-C), total cholesterol (TC)]. In addition, CGA significantly increased the content of blood very-long-chain fatty-acid (VLCFA)-containing ceramides species. This could be explained mechanically by a distinction between LJF and CGA's effects on C1q/TNF-related proteins (CTRPs) which activate adiponectin receptors, triggering several downstream reactions. Because both LJF and CGA upregulated liver expression of adiponectin receptors (AdipoR1 and AdipoR2) and enhanced the activity of downstream AMPK. LJF also increased serum levels of CTRP3 and CTRP9, especially CTRP9, whereas CGA had higher serum CTRP3 and upregulated liver PPARa expression. Additionally, ELOVL6 expression in the liver was greater in CGA than LJF. This study demonstrates that LJF and CGA exert hypoglycemic and lipid modulation capacity to prevent prediabetes may through the CTRPs-AdipoRs-AMPK/PPARα axes and promoting ELOVL6 protein expression.

Pathophysiology, phenotypes and management of type 2 diabetes mellitus in Indian and Chinese populations

Nearly half of all adults with type 2 diabetes mellitus (T2DM) live in India and China. These populations have an underlying predisposition to deficient insulin secretion, which has a key role in the pathogenesis of T2DM. Indian and Chinese people might be more susceptible to hepatic or skeletal muscle insulin resistance, respectively, than other populations, resulting in specific forms of insulin deficiency. Cluster-based phenotypic analyses demonstrate a higher frequency of severe insulin-deficient diabetes mellitus and younger ages at diagnosis, lower β-cell function, lower insulin resistance and lower BMI among Indian and Chinese people compared with European people. Individuals diagnosed earliest in life have the most aggressive course of disease and the highest risk of complications. These characteristics might contribute to distinctive responses to glucose-lowering medications. Incretin-based agents are particularly effective for lowering glucose levels in these populations; they enhance incretin-augmented insulin secretion and suppress glucagon secretion. Sodium-glucose cotransporter 2 inhibitors might also lower blood levels of glucose especially effectively among Asian people, while α-glucosidase inhibitors are better tolerated in east Asian populations versus other populations. Further research is needed to better characterize and address the pathophysiology and phenotypes of T2DM in Indian and Chinese populations, and to further develop individualized treatment strategies.

Predictive Effect of Triglyceride Glucose-Related Parameters, Obesity Indices, and Lipid Ratios for Diabetes in a Chinese Population: A Prospective Cohort Study

Objective

The purpose of this study was to evaluate the association between triglyceride glucose (TyG) index and new-onset diabetes under different glycemic states and to compare the predictive value of TyG-related parameters, obesity indices, and lipid ratios for new-onset diabetes.

Methods

Data were collected from the China Health and Retirement Longitudinal Study (CHARLS), consisting of 6,258 participants aged ≥45 years. Participants were grouped according to their glycemic states. Cox proportional hazards models and restricted cubic spline regression were used to explore the association between TyG index and diabetes. Cox proportional hazard models were applied to confirm the predictive value of the optimal marker. Receiver operating characteristic (ROC) curves were used to compare the predictive value.

Results

TyG index was positively correlated with the risk of diabetes (hazard ratio (HR), 1.75; 95% confidence interval (CI), 1.56-1.97), and the linear association existed (p < 0.001). The highest correlation with diabetes was visceral adiposity index (VAI) (HR, 2.04; 95% CI, 1.44-2.90) in normal fasting glucose (NFG) group and TyG-body mass index (TyG-BMI) (HR, 2.53; 95% CI, 1.97-3.26) in impaired fasting glucose (IFG) group. The largest area under curve (AUC) was observed in TyG-waist-to-height ratio (TyG-WHtR) in the NFG group (AUC, 0.613; 95% CI, 0.527-0.700), and TyG-BMI had the highest AUC in the IFG group (AUC, 0.643; 95% CI, 0.601-0.685).

Conclusion

The association between TyG index and new-onset diabetes was positive and linear. TyG-WHtR was a clinically effective marker for identifying the risks of diabetes in the NFG group and TyG-BMI was an effective marker to predict diabetes in the IFG group.

Outcome of lifestyle intervention in relation to duration of pre-diabetes: the Pathobiology and Reversibility of Prediabetes in a Biracial Cohort (PROP-ABC) study

INTRODUCTION

In studies that enrolled people with prevalent pre-diabetes of unknown duration, lifestyle intervention (LI) delayed progression to type 2 diabetes (T2D) but did not reverse pre-diabetes in most participants. Here, we assessed the effects of LI among individuals with pre-diabetes of known duration to determine whether outcomes are related to duration of pre-diabetes.

RESEARCH DESIGN AND METHODS

The Pathobiology and Reversibility of Prediabetes in a Biracial Cohort study initiated LI in subjects with incident pre-diabetes during follow-up of initially normoglycemic African Americans and European Americans with parental T2D. Participants were stratified into those initiating LI after <3, 3-5, or >5 years of pre-diabetes diagnosis. Assessments included anthropometry, body fat, fasting and 2-hour plasma glucose (FPG, 2hPG), and insulin sensitivity and secretion. The outcomes were normal glucose regulation (NGR; ie, normal FPG and 2hPG), persistent pre-diabetes, or T2D. Participants who maintained normal FPG and normal 2hPG levels during follow-up served as the control. The control subjects did not receive lifestyle or other intervention to alter the course of glycemia or body weight.

RESULTS

Of 223 participants (age 53.3±9.28 years, body mass index 30.6±6.70 kg/m²), 72 (control) maintained normoglycemia during follow-up and 138 subjects with incident pre-diabetes initiated LI after 4.08±2.02 years (range 3 months-8.3 years) of diagnosis. Compared with control, LI participants showed decrease in glucose, weight, and body fat; 42.8% reverted to NGR, 50% had persistent pre-diabetes, and 7.2% developed T2D after 5 years. These outcomes were similar across race and pre-diabetes duration strata, but greater glycemic decrease occurred when LI was initiated within 5 years of pre-diabetes diagnosis.

CONCLUSIONS

Ninety-three per cent of adults with parental T2D who initiated LI within 3 months to 8.3 years of developing pre-diabetes did not progress to T2D; nearly half reverted to NGR.Trial registration number NCT02027571.

The Long-Term Effects of Non-Pharmacological Interventions on Diabetes and Chronic Complication Outcomes in Patients With Hyperglycemia: A Systematic Review and Meta-Analysis

OBJECTIVE

This study aimed at examining the long-term effects of non-pharmacological interventions on reducing the diabetes incidence among patients with prediabetes and chronic complications events among patients with hyperglycemia (pre-diabetes and diabetes) by performing a systematic review and meta-analysis of randomized controlled trials (RCTs).

METHODS

PubMed, MEDLINE, EMBASE, the Cochrane Library, and the Web of Science Core Collection were searched for studies published between January 1990 and November 2021, looking for RCTs to evaluate the effects of non-pharmacological interventions on preventing the incidence of diabetes and chronic complications in comparison with medical therapy, placebo, or usual diabetes care. Two independent reviews extracted relevant data and quality assessment. Any discrepancies were resolved by a third reviewer.

RESULTS

In total, 20 articles involved 16 RCTs (follow-up ranged from 2 to 30 years) were included. Pooled analysis of intervention studies demonstrated clearly that non-pharmacological interventions have a significant effect on reducing the diabetes events in patients with prediabetes (RR 0.62; 95% CI 0.54, 0.71). Pooled analysis of extended follow-up studies showed that non-pharmacological interventions could effectively reduce the diabetes incidence in patients with prediabetes (RR 0.78; 95% CI 0.63, 0.96). Meta-regression and subgroup analysis indicates that the diabetes incidence of the long-term group (duration > 3 years) was clearly reduced by 0.05% compared with the relatively short-term group (duration ≤ 3 years). The incidence of microvascular complications in patients with hyperglycemia was effectively lowered by non-pharmacological interventions (RR 0.60; 95% CI 0.43, 0.83).

CONCLUSION

Non-pharmacological interventions have a long-term effect on reducing the diabetes incidence among prediabetic patients and effectively preventing microvascular complications on hyperglycemia.

SYSTEMATIC REVIEW REGISTRATION

https://www.crd.york.ac.uk/prospero/.

Serum osteopontin predicts glycaemic profile improvement in metabolic syndrome: A pilot study

Prediabetes is often observed in patients with Metabolic Syndrome (MetS) and might be associated with metabolic and inflammatory alterations. Here, we investigated whether the inflammatory molecule osteopontin (OPN) might have a prognostic impact in a cohort of MetS patients (n = 85) with baseline normal glycaemia or impaired fasting glucose (IFG) over one year of recommended pharmacological treatments and Mediterranean diet. Patients were then followed up for 12 months with intermediate evaluation after 6 months. At all time points, anthropometric and clinical data were recorded, alongside with haematological and biochemical profiles, including serum concentrations of OPN. As expected, Mediterranean diet improves glycaemic profile in patients with IFG. Baseline serum OPN failed to be associated with baseline anthropometric or biochemical variables. At baseline, higher levels of OPN were shown in patients with IFG as compared to normal glycaemia. Two distinct subgroups of patients in whom OPN decreased or remained stable/increased at follow-up were identified. When higher serum OPN levels were observed at baseline, greater reduction was observed at 1-year follow-up. Reduction in circulating OPN levels was associated with metabolic improvement in terms of blood pressure, LDL-c, HDL-c, and glycaemia. At both univariate and adjusted logistic regression analyses, serum OPN emerged as an independent predictor of glycaemic profile improvement at 1-year follow-up (adjOR 1.05 [1.00-1.10]; P = .041). In conclusion, pharmacological and dietetic interventions improved glycaemic profile in patients with MetS. In particular, glycaemic improvement was demonstrated in patients who also reduce circulating OPN levels. Higher OPN levels at baseline predict normalization of glycaemic profile.

Clinical and metabolomic predictors of regression to normoglycemia in a population at intermediate cardiometabolic risk

Background

Impaired fasting glucose (IFG) is a prevalent and potentially reversible intermediate stage leading to type 2 diabetes that increases risk for cardiometabolic complications. The identification of clinical and molecular factors associated with the reversal, or regression, from IFG to a normoglycemia state would enable more efficient cardiovascular risk reduction strategies. The aim of this study was to identify clinical and biological predictors of regression to normoglycemia in a non-European population characterized by high rates of type 2 diabetes.

Methods

We conducted a prospective, population-based study among 9637 Mexican individuals using clinical features and plasma metabolites. Among them, 491 subjects were classified as IFG, defined as fasting glucose between 100 and 125 mg/dL at baseline. Regression to normoglycemia was defined by fasting glucose less than 100 mg/dL in the follow-up visit. Plasma metabolites were profiled by Nuclear Magnetic Resonance. Multivariable cox regression models were used to examine the associations of clinical and metabolomic factors with regression to normoglycemia. We assessed the predictive capability of models that included clinical factors alone and models that included clinical factors and prioritized metabolites.

Results

During a median follow-up period of 2.5 years, 22.6% of participants (n = 111) regressed to normoglycemia, and 29.5% progressed to type 2 diabetes (n = 145). The multivariate adjusted relative risk of regression to normoglycemia was 1.10 (95% confidence interval [CI] 1.25 to 1.32) per 10 years of age increase, 0.94 (95% CI 0.91–0.98) per 1 SD increase in BMI, and 0.91 (95% CI 0.88–0.95) per 1 SD increase in fasting glucose. A model including information from age, fasting glucose, and BMI showed a good prediction of regression to normoglycemia (AUC = 0.73 (95% CI 0.66–0.78). The improvement after adding information from prioritized metabolites (TG in large HDL, albumin, and citrate) was non-significant (AUC = 0.74 (95% CI 0.68–0.80), p value = 0.485).

Conclusion

In individuals with IFG, information from three clinical variables easily obtained in the clinical setting showed a good prediction of regression to normoglycemia beyond metabolomic features. Our findings can serve to inform and design future cardiovascular prevention strategies.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12933-021-01246-1.

Complex patterns of circulating fatty acid levels in gestational diabetes mellitus subclasses across pregnancy

BACKGROUND & AIMS

To investigate the relationship between maternal serum fatty acid levels and gestational diabetes mellitus (GDM) subtypes across pregnancy.

METHODS

A total of 680 singleton mothers enrolled in the Complex Lipids in Mothers and Babies (CLIMB) study in Chongqing, China were included. Clinical information and serum samples were collected at gestational weeks (GWs) 11-14, 22-28, and 32-34. 75 g Oral Glucose Tolerance Test (OGTT) was conducted at GW 24-28 and GDM subtypes divided into three groups using International Association of Diabetes and Pregnancy Study Group (IADPSG) guidelines criteria: elevated fasting plasma glucose (FPG group; n = 59); 1-h and/or 2-h post-load glucose (1h/2h-PG group; n = 94); combined group (FPG&1h/2h-PG group; n = 42). Non-GDM pregnancies were included (n = 485) as controls. Twenty fatty acids were quantified in serum using gas chromatography-mass spectrometry (GC-MS) analysis.

RESULTS

Overall, most serum fatty acid concentrations increased rapidly from the first to second trimester, followed by a plateauing or reduction in the third trimester (p < 0.001). In cross sectional analysis, fatty acid concentrations were significantly higher in the FPG group at GW 11-14 and decreased in the 1h/2h-PG group at GW 32-34, relative to controls. Moreover, higher α-linolenic acid (ALA; the second tertile: adjusted odds ratio [aOR] = 2.53, 95% CI: 1.17 to 5.47; the third tertile: aOR = 2.60, 95% CI: 1.20 to 5.65) and docosahexaenoic acid (DHA; the second tertile: aOR = 2.34, 95% CI: 1.10 to 4.97; the third tertile: aOR = 2.16, 95% CI: 1.00 to 4.63) were significantly associated with a higher risk of GDM in women with elevated fasting plasma glucose at GW 11-14 (first tertile as reference).

CONCLUSIONS

Our findings highlight the importance of considering GDM subtypes for the individualised management of GDM in pregnancy. ALA and DHA in early pregnancy are associated with a higher risk of FPG-GDM subtype. This has widespread implications when recommending n-3 PUFAs supplementation for women with GDM.

Pre-Stroke Glycemic Variability Estimated by Glycated Albumin Is Associated with Early Neurological Deterioration and Poor Functional Outcome in Prediabetic Patients with Acute Ischemic Stroke

<b><i>Introduction:</i></b> Whether glycemic variability prior to stroke increases the risk of stroke outcomes in prediabetic patients presenting with acute ischemic stroke is still unclear. We evaluated whether pre-stroke glycemic variability, estimated by glycated albumin (GA), increased early neurological deterioration (END) and functional outcomes in prediabetic patients with acute ischemic stroke. <b><i>Methods:</i></b> A total of 215 acute ischemic stroke patients with prediabetes were evaluated. The primary outcome was END, defined as an incremental increase in the National Institutes of Health Stroke Scale score by ≥1 point in motor power or ≥2 points in the total score within the 7 days after admission. The secondary outcome was poor functional status defined by a modified Rankin Scale at 3 months. Higher GA (≥16.0%) was determined to reflect glycemic fluctuation prior to ischemic stroke. <b><i>Results:</i></b> Of the 215 prediabetic patients, 77 (35.8%) were in the higher GA group. In prediabetic patients, END occurrence and poor functional status were higher in the higher GA group than in the lower GA group. The multivariate analysis showed that a higher GA was associated with an increased risk of END occurrence and poor functional outcomes at 3 months (adjusted odds ratio [95% confidence interval], 4.58 [1.64–12.81], <i>p</i> = 0.004 and 2.50 [1.19–5.25], <i>p</i> = 0.02, respectively). <b><i>Conclusion:</i></b> Pre-stroke glycemic variability estimated by GA was associated with END occurrence and poor functional outcome after ischemic stroke in patients with prediabetes.

Chronic Microvascular Complications in Prediabetic States-An Overview

A prediabetic state is a major risk factor for the development of diabetes, and, because of an identical pathophysiological background of both conditions, their prevalence increases parallelly and equally fast. Long-term hyperglycemia is the main cause inducing chronic complications of diabetes, yet the range of glucose levels at which they start has not been yet unequivocally determined. The current data show that chronic microvascular complications of diabetes can be observed in patients with abnormal glucose metabolism in whom glycaemia is higher than optimal but below diagnostic criteria for diabetes. Prediabetes is a heterogenous nosological unit in which particular types are differently characterized and show different correlations with particular kinds of complications. Analysis of the latest research results shows the need to continue studies in a larger population and can imply the need to verify the currently employed criteria of diagnosing diabetes and chronic complications of diabetes in people with prediabetes.

Prediabetes Deserves More Attention: A Review

Evidence increasingly demonstrates that prediabetes is a toxic state, as well as a risk factor for diabetes, and is associated with pathophysiological changes in several tissues and organs. Unfortunately, use of available evidence-based treatments for prediabetes is low. This review seeks to explain why prediabetes must be viewed and treated as a serious pathological entity in its own right. It offers an overview of the pathophysiology and complications of prediabetes and describes how this condition can be reversed if all treatment avenues are deployed early in its course.

The effects of green coffee extract supplementation on glycemic indices and lipid profile in adults: a systematic review and dose-response meta-analysis of clinical trials

Background

The role of coffee consumption in the risk of cardiovascular diseases has been debated for many years. The current study aimed to summarize earlier evidence on the effects of green coffee extract (GCE) supplementation on glycemic indices and lipid profile.

Methods

We searched available online databases for relevant clinical trials published up to October 2019. All clinical trials investigating the effect of GCE supplementation, compared with a control group, on fasting blood glucose (FBG), serum insulin, total cholesterol (TC), triglyceride (TG), low-density lipoprotein (LDL), and high-density lipoprotein (HDL) were included. Overall, 14 clinical trials with a total sample size of 766 participants were included in the current meta-analysis.

Results

We found a significant reducing effect of GCE supplementation on FBG (weighted mean difference (WMD): -2.35, 95% CI: − 3.78, − 0.92 mg/dL, P = 0.001) and serum insulin (WMD: -0.63, 95% CI: − 1.11, − 0.15 μU/L, P = 0.01). With regard to lipid profile, we observed a significant reduction only in serum levels of TC following GCE supplementation in the overall meta-analysis (WMD: -4.51, 95% CI: − 8.39, − 0.64, P = 0.02). However, subgroup analysis showed a significant reduction in serum TG in studies enrolled both genders. Also, such a significant reduction was seen in serum levels of LDL and HDL when the analyses confined to studies with intervention duration of ≥8 weeks and those included female subjects. In the non-linear dose-response analyses, we found that the effects of chlorogenic acid (CGA) dosage, the main polyphenol in GCE, on FBG, TG and HDL were in the non-linear fashions.

Conclusion

In conclusion, we found that GCE supplementation improved FBG and serum levels of insulin and TC. Also, there was a significant improvement in other markers of lipid profile in some subgroups of clinical trials.

Influence of Cinnamon on Glycemic Control in Individuals With Prediabetes: A Randomized Controlled Trial

Context

The identification of adjunct safe, durable, and cost-effective approaches to reduce the progression from prediabetes to type 2 diabetes (T2D) is a clinically relevant, unmet goal. It is unknown whether cinnamon’s glucose-lowering properties can be leveraged in individuals with prediabetes.

Objective

The objective of this work is to investigate the effects of cinnamon on measures of glucose homeostasis in prediabetes.

Design, Setting, Participants, and Intervention

This double-blind, placebo-controlled, clinical trial randomly assigned adult individuals meeting any criteria for prediabetes to receive cinnamon 500 mg or placebo thrice daily (n = 27/group). Participants were enrolled and followed at 2 academic centers for 12 weeks.

Main Outcome Measures

Primary outcome was the between-group difference in fasting plasma glucose (FPG) at 12 weeks from baseline. Secondary end points included the change in 2-hour PG of the oral glucose tolerance test (OGTT), and the change in the PG area under the curve (AUC) derived from the OGTT.

Results

From a similar baseline, FPG rose after 12 weeks with placebo but remained stable with cinnamon, leading to a mean between-group difference of 5 mg/dL (P < .05). When compared to the respective baseline, cinnamon, but not placebo, resulted in a significant decrease of the AUC PG (P < .001) and of the 2-hour PG of the OGTT (P < .05). There were no serious adverse events in either study group.

Conclusions

In individuals with prediabetes, 12 weeks of cinnamon supplementation improved FPG and glucose tolerance, with a favorable safety profile. Longer and larger studies should address cinnamon’s effects on the rate of progression from prediabetes to T2D.

Pathobiology and Reversibility of Prediabetes in a Biracial Cohort (PROP-ABC) Study: design of lifestyle intervention

INTRODUCTION

Intensive lifestyle intervention (ILI) prevents progression from prediabetes to type 2 diabetes (T2D) but reversal of prediabetes is less well studied.

RESEARCH DESIGN AND METHODS

The overall objectives of the Pathobiology and Reversibility of Prediabetes in a Biracial Cohort (PROP-ABC) Study (ClinicalTrials.gov ID: NCT02027571) are to determine the natural history and reversibility of prediabetes. The study tests specific hypotheses on the patterns of progression to prediabetes among normoglycemic African-American (AA) and European-American (EA) offspring of parents with T2D; emergence of microvascular and macrovascular complications during transition from normal to impaired glucose regulation; significance of the 'metabolically healthy' obese phenotype; and effect of duration of the prediabetic state on its reversibility with lifestyle intervention. Participants who developed incident prediabetes were offered ILI and evaluated quarterly for 5 years. The primary outcome was restoration of normal glucose regulation (fasting plasma glucose <100 mg/dL and two-hour plasma glucose (2hrPG)<140 mg/dL).

RESULTS

Of the 223 subjects enrolled in the PROP-ABC Study, 158 participants with incident prediabetes started ILI. The mean age was 53.3±9.28 years; body mass index 30.6±6.70 kg/m²; 70% were female, 52.4% AA and 47.6% EA. The ILI program used goal setting, weight-based calorie restriction, physical activity (180 min/week), self-monitoring, and meal replacement. Monthly face-to-face (F2F) counseling sessions during the initial 6 months, and quarterly visits thereafter, were supplemented with electronic and postal contacts. Attendance at F2F sessions was highly correlated with weight loss (r=0.98, p<0.0001). Meal replacement induced ~5 kg weight loss within 3 months in participants with recrudescent weight pattern. Self-reported exercise minutes correlated with pedometer step counts (r=0.47, p<0.0001).

CONCLUSION

The PROP-ABC Study has demonstrated the feasibility of executing an ILI program designed to test reversibility of incident prediabetes in a biracial cohort.

Impact of Glucose Level on Micro- and Macrovascular Disease in the General Population: A Mendelian Randomization Study

OBJECTIVE

To evaluate whether high glucose levels in the normoglycemic range and higher have a causal genetic effect on risk of retinopathy, neuropathy, nephropathy, chronic kidney disease (CKD), peripheral arterial disease (PAD), and myocardial infarction (MI; positive control) in the general population.

RESEARCH DESIGN AND METHODS

This study applied observational and one-sample Mendelian randomization (MR) analyses to individual-level data from 117,193 Danish individuals, and validation by two-sample MR analyses on summary-level data from 133,010 individuals from the Meta-Analyses of Glucose and Insulin-Related Traits Consortium (MAGIC), 117,165 from the CKDGen Consortium, and 452,264 from the UK Biobank.

RESULTS

Observationally, glucose levels in the normoglycemic range and higher were associated with high risks of retinopathy, neuropathy, diabetic nephropathy, PAD, and MI (all P for trend <0.001). In genetic causal analyses, the risk ratio for a 1 mmol/L higher glucose level was 2.01 (95% CI 1.18-3.41) for retinopathy, 2.15 (1.38-3.35) for neuropathy, 1.58 (1.04-2.40) for diabetic nephropathy, 0.97 (0.84-1.12) for estimated glomerular filtration rate (eGFR) <60 mL/min/1.73 m², 1.19 (0.90-1.58) for PAD, and 1.49 (1.02-2.17) for MI. Summary-level data from the MAGIC, the CKDGen Consortium, and the UK Biobank gave a genetic risk ratio of 4.55 (95% CI 2.26-9.15) for retinopathy, 1.48 (0.83-2.66) for peripheral neuropathy, 0.98 (0.94-1.01) for eGFR <60 mL/min/1.73 m², and 1.23 (0.57-2.67) for PAD per 1 mmol/L higher glucose level.

CONCLUSIONS

Glucose levels in the normoglycemic range and higher were prospectively associated with a high risk of retinopathy, neuropathy, diabetic nephropathy, eGFR <60 mL/min/1.73 m², PAD, and MI. These associations were confirmed in genetic causal analyses for retinopathy, neuropathy, diabetic nephropathy, and MI, but they could not be confirmed for PAD and seemed to be refuted for eGFR <60 mL/min/1.73 m².

Insulin resistance, beta-cell function, adipokine profiles and cardiometabolic risk factors among Chinese youth with isolated impaired fasting glucose versus impaired glucose tolerance: the BCAMS study

OBJECTIVE

Impaired fasting glucose (IFG) and impaired glucose tolerance (IGT) may convey disparate risks of metabolic consequences. Fasting plasma glucose (FPG), while an expedient screening procedure, may not adequately assess metabolic risk, particularly among youths. In order to inform a strategy for screening Chinese youth for pre-diabetes, we examined the relative value of IFG versus IGT to define metabolic risk by assessing their association with insulin resistance, beta-cell dysfunction, adverse adipokine profiles and other cardiometabolic risk factors.

RESEARCH DESIGN AND METHODS

We recruited 542 subjects (age 14-28 years) from the Beijing Child and Adolescent Metabolic Syndrome study for an in-depth assessment of cardiometabolic risk factors, including a 2-hour oral glucose tolerance test, liver ultrasound and serum levels of four adipokines.

RESULTS

FPG failed to identify nearly all (32/33) youths with IGT, whereas 2-hour plasma glucose (2 h PG) missed 80.8% (21/26) of subjects with IFG. Impaired beta-cell function was evident from decreased oral disposition indices in those with isolated impaired fasting glucose (iIFG) or isolated impaired glucose tolerance (iIGT) versus normal glucose tolerance (NGT) (all p<0.001), whereas reduced insulin sensitivity (Matsuda) index was most pronounced in the iIGT group (p<0.01). Moreover, alterations in adipokine levels (fibroblast growth factor 21, adiponectin and leptin/adiponectin ratio) were associated with iIGT (p<0.05) but not iIFG. Youths with iIGT had a 2-fold to 32-fold increased incidence of hypertriglyceridemia, hypertension and metabolic syndrome (MetS) compared with those with NGT. In addition, subgroup analyses of participants with normal FPG revealed that the odds of having IGT increased 3-fold to 18-fold among those with elevated TGs, hypertension, moderate-to-severe non-alcoholic fatty liver disease or MetS.

CONCLUSIONS

Chinese youth with iIGT exhibit a higher cardiometabolic risk profile than those with iIFG. Thus, 2 h PG is preferred over FPG to identify the pre-diabetes phenotype at greatest risk of subsequent development of cardiovascular disease.

TRIAL REGISTRATION NUMBER

NCT03421444.

Health risks and interventions in prediabetes: A review

Prediabetes is a condition which appears prior to the development of diabetes in which blood glucose is abnormally high but do not reach the diagnostic threshold of type 2 diabetes mellitus. It is characterized by a cluster of metabolic abnormalities viz. dysglycemia, dyslipidemia, hypertension, physical inactivity, obesity, insulin resistance, procoagulant state, endothelial dysfunction, oxidative stress and inflammation, placing prediabetic subjects to an increased risk for diabetes and its complications. Recent studies demonstrate that complications of diabetes i.e. microvascular and macrovascular complications may manifest in some prediabetic subjects. This article reviews prediabetes-related risk factors and health issues. In addition, this article also highlights the interventions to prevent the development of diabetes in prediabetic subjects.

Assessment of glucose variability in subjects with prediabetes

The aim of the study was to assess glucose variability in subjects with prediabetes by means of CGM.

MATERIAL AND METHODS

32 subjects with prediabetes - mean age 56.6 ± 9.6 years, mean BMI 30.3 ± 5.3 kg/m² and 18 subjects with normal glucose tolerance (NGT) - mean age 54.4 ± 9.9 years, mean BMI 24.8 ± 6.9 kg/m², were enrolled. Glucose tolerance was studied during OGTT. HbA1c was measured by NGSP certified method. CGM was performed with FreeStyle Libre Pro sensor.

RESULTS

The following indices of glucose variability were significantly higher in the prediabetes group - CV (p < 0.041), J-index (p < 0.014), CONGA (p < 0.047) and GRADE (p < 0.036). A significant increase in HbA1c (p < 0.036), mean interstitial glucose (p < 0.025), time above range (p < 0.018) and a significant decrease in time in range (p < 0.014) was found in prediabetes compared to NGT. Significant correlations between HbA1c and LBGI (r = -0.33, p = 0.02), HBGI (r = 0.31, p = 0.03), CONGA (r = 0.36, p = 0.01), J-index (r = 0.37, p = 0.01) and M-value (r = -0.34, p = 0.02) were established.

CONCLUSION

Glucose variability is significantly increased in prediabetes and is an additional parameter in the assessment of glucose homeostasis even at these early stages of glucose dysregulation.

Risk factors for developing diabetes after 3 years among community-dwelling elderly with impaired fasting glucose

BACKGROUND

The aim of the present study was to examine the risk factors for developing diabetes after 3 years in an elderly Chinese suburban population with impaired fasting glucose (IFG).

METHODS

The study population comprised residents of the Hangu area of Tianjin, China, with IFG, aged ≥60 years, who joined the national free physical examination program (n = 328; mean [±SD] age 68.0 ±6.1 years; 48.2% men). Diabetes was defined by self-report of a physician's diagnosis or fasting plasma glucose (FPG) ≥7.0 mmol/L; IFG was defined as FPG ≥5.6 and < 7.0 mmol/L. Risk factors of incident diabetes at the 3-year follow-up were analyzed individually using logistic regression analysis.

RESULTS

Between baseline and the 3-year follow-up, 56 subjects with IFG at baseline had developed diabetes. After multivariate adjustment for demographic and clinical factors, the incidence of diabetes increased with higher FPG (odds ratio [OR] 9.30, 95% confidence interval [CI] 2.84-30.48), but decreased with the grip strength/weight ratio (OR 0.88, 95% CI 0.82-0.94). Moreover, the combination of higher FPG and lower grip strength/weight was associated with a higher incidence of diabetes than higher FPG only or lower grip strength/weight (P < 0.05).

CONCLUSION

The present study indicates that higher FPG and lower muscle strength are associated with glycemic deterioration among subjects with IFG after 3 years. The results suggest that not only glucose levels, but also physical performance may be useful markers of the risk of diabetes in this population.

Effect of Chlorogenic Acid Administration on Glycemic Control, Insulin Secretion, and Insulin Sensitivity in Patients with Impaired Glucose Tolerance

Chlorogenic acid has been described as a novel polyphenol with metabolic effects on glucose homeostasis. The aim of this study was to evaluate the effect of chlorogenic acid administration on glycemic control, insulin secretion, and insulin sensitivity in patients with impaired glucose tolerance (IGT). A randomized, double-blind, placebo-controlled clinical trial was performed in 30 patients with IGT; 15 patients randomly assigned to oral chlorogenic acid received 400 mg three times per day for 12 weeks, and the other 15 patients received placebo in the same way. Before and after the intervention, anthropometric and metabolic measurements, including fasting plasma glucose (FPG), glycated hemoglobin A1c, and a lipid profile, were performed. Area under the curve of glucose and insulin as well as the insulinogenic, Stumvoll, and Matsuda indices were calculated. Wilcoxon, Mann-Whitney U, and chi-square tests were performed, and P ≤ .05 was considered statistically significant. There were significant decreases in FPG (5.7 ± 0.4 vs. 5.5 ± 0.4 mmol/L, P = .002), insulinogenic index (0.71 ± 0.25 vs. 0.63 ± 0.25, P = .028), body weight, body mass index, waist circumference, triglycerides, total cholesterol, low-density lipoprotein cholesterol, and very low-density lipoprotein levels in the chlorogenic acid group, with an increment in the Matsuda index (1.98 ± 0.88 vs. 2.30 ± 1.23, P = .002). There were no significant differences in the placebo group. In conclusion, chlorogenic acid administration in patients with IGT decreased FPG and insulin secretion, while increasing insulin sensitivity and improving both anthropometric evaluations and the lipid profile.

Relationships between blood pressure and blood glucose among offspring of parents with type 2 diabetes: Prediction of incident dysglycemia in a biracial cohort

AIMS

We assessed blood pressure (BP) and blood glucose (BG) values in healthy subjects, and examined baseline BP as a predictor of incident prediabetes during follow-up.

METHODS

Participants in the Pathobiology of Prediabetes in a Biracial Cohort (POP-ABC) study underwent screening assessments (anthropometry, BP, OGTT) and were stratified into normal BP (NBP), prehypertension, or hypertension, and normal glucose regulation (NGR), prediabetes (IFG/IGT), or type 2 diabetes (T2D) status. NGR subjects who met all inclusion criteria were enrolled in a 5-yr prospective study, with the primary outcome of incident prediabetes.

RESULTS

We screened 602 adults (341 black, 261 white) and enrolled 343 (193 black, 150 white) for prospective follow-up. Systolic and diastolic BP correlated significantly with fasting and nonfasting BG (P=0.003-<0.0001). Compared to NGR group, more prediabetic subjects had prehypertension (42.5% vs. 36.2%) and fewer had NBP (35.9% vs. 48.6%) (P=0.009). During ~5years of follow-up, 26.3% of NBP and 35.7% of prehypertensive subjects developed prediabetes (P=0.02). Kaplan-Meier analysis showed higher probability of incident prediabetes among participants with prehypertension compared to NBP during ~5years of follow-up (P=0.0012).

CONCLUSIONS

In our biracial cohort, BP and BG values were significantly correlated, and BP status predicted incident prediabetes among initially normoglycemic individuals. These findings suggest co-evolution of factors involved in the dysregulation of BP and BG.

Haemoglobin A1c as a screening tool for type 2 diabetes and prediabetes in populations of Swedish and Middle-East ancestry

AIMS

To explore and compare sensitivity and specificity for HbA1c ≥48mmol/mol as a predictor for type 2 diabetes mellitus (T2DM) in two populations with different ethnicity and to examine the predictive value of two levels of HbA1c (≥42mmol/mol, ≥39mmol/mol) for prediabetes in these populations.

METHODS

Four cohorts were examined with an oral glucose tolerance test. (1) The MEDIM Study (n=1991 individuals of Swedish and Iraqi ancestry); (2) The Skaraborg Project (n=1327 individuals of Swedish ancestry); (3) The 4-D study (n=424 individuals of Swedish, Iraqi and Turkish ancestry); (4) The Flemingsberg study (n=212 participants of Turkish ancestry).

RESULTS

HbA1c ≥48mmol/mol had a sensitivity for T2DM of 31% and 25% respectively in individuals of Middle-East and Swedish ancestry. The positive and negative predictive value was high in both populations (70.3, 96.4 and 96.2, 97.6 respectively). Using HbA1c ≥42mmol/mol and ≥39mmol/mol as a predictor for prediabetes gave a sensitivity of 17% and 36% in individuals of Middle-East and 15% and 34% in individuals of Swedish ancestry.

CONCLUSIONS

Even if HbA1c ≥48mmol/mol is a valuable diagnostic tool, it is a blunt and insensitive tool for screening and would exclude most people with T2DM, independent of ancestry and age. HbA1c is an inefficient way to detect individuals with prediabetes.

Predictive models for conversion of prediabetes to diabetes

AIM

To clarify the natural course of prediabetes and develop predictive models for conversion to diabetes.

METHODS

A retrospective longitudinal study of 2105 adults with prediabetes was carried out with a mean observation period of 4.7years. Models were developed using multivariate logistic regression analysis and verified by 10-fold cross-validation. The relationship between [final BMI minus baseline BMI] (δBMI) and incident diabetes was analyzed post hoc by comparing the diabetes conversion rate for low (< -0.31kg/m²) and high δBMI (≥ -0.31kg/m²) subjects after matching the two groups for the covariates.

RESULTS

Diabetes developed in 252 (2.5%/year), and positive family history, male sex, higher systolic blood pressure, plasma glucose (fasting and 1h- and 2h-values during 75g OGTT), hemoglobin A1c (HbA1c) and alanine aminotransferase were significant, independent predictors for the conversion. By using a risk score (RS) that took account of all these variables, incident diabetes was predicted with an area under the ROC curve (95% CI) of 0.80 (0.70-0.87) and a specificity of prediction of 61.8% at 80% sensitivity. On division of the participants into high- (n=248), intermediate- (n=336) and low-risk (n=1521) populations, the conversion rates were 40.1%, 18.5% and 5.9%, respectively. The conversion rate was lower in subjects with low than high δBMI (9.2% vs 14.4%, p=0.003).

CONCLUSIONS

Prediabetes conversion to diabetes could be predicted with accuracy, and weight reduction during the observation was associated with lowered conversion rate.

Post-Glucose Load Measures of Insulin Resistance and Prognosis of Nondiabetic Patients With Ischemic Stroke

Background

Insulin resistance is associated with an increased risk of cardiovascular events in the general population. This study aimed to estimate the association between post–glucose load measures of insulin resistance and prognosis of nondiabetic patients with ischemic stroke.

Methods and Results

Data were derived from the ACROSS‐China (Abnormal Glucose Regulation in Patients with Acute Stroke across China) registry. Patients with ischemic stroke without a history of diabetes mellitus were included. Two post–glucose load measures of insulin sensitivity, the insulin sensitivity indices ISI(composite) and the ISI_0,120, were calculated. Outcomes included stroke recurrence, all‐cause death, and poor functional outcome at 12 months. Among 1203 patients, 63.3% were male with an average age of 62.1 years. At 12 months, 168 (14.4%) patients had recurrent stroke, 111 (9.2%) had died, and 288 (24.4%) had poor outcome. After adjustment for potential covariates, the first quartile of the ISI(composite) was associated with increased 12‐month stroke recurrence (adjusted hazard ratio 2.02, 95% CI 1.28–3.18, P=0.003), death (adjusted hazard ratio 2.78, 95% CI 1.59–4.86, P<0.001), and poor outcome (adjusted odds ratio 2.67, 95% CI 1.69–4.21, P<0.001) compared with the fourth quartile. Similar results were observed for the ISI_0,120 but with a larger magnitude of association. Using a multivariable regression model with restricted cubic spline, we found an L‐shaped association between the insulin sensitivity indices and the risk of each end point.

Conclusions

In this large‐scale registry, post–glucose load measures of insulin resistance with the ISI(composite) and the ISI_0,120 were associated with 12‐month poor outcomes of nondiabetic patients with ischemic stroke.

Enhancing Exercise Responsiveness across Prediabetes Phenotypes by Targeting Insulin Sensitivity with Nutrition

Exercise is a cornerstone therapy for chronic diseases related to multiorgan insulin resistance. However, not all individuals show the anticipated improvement in insulin sensitivity following exercise and these individuals are considered exercise resistant. Caloric restriction is an approach to enhance the effect of exercise on increasing peripheral and hepatic insulin sensitivity, as replenishing expended calories blunts these benefits. Alternatively, restricting carbohydrate intake, independent of energy balance, following exercise provides an additive effect on peripheral insulin sensitivity when compared to refeeding carbohydrate. Although carbohydrate composition modulates insulin sensitivity, few have studied effects of low glycemic index or whole-grain diets following exercise across prediabetes phenotypes on insulin sensitivity. Herein, we propose the novel hypothesis that the combination of individualized nutrition therapy and exercise should be based on the clinical pathology of prediabetes to overcome exercise resistance and improve responsiveness in people at risk for type 2 diabetes and cardiovascular disease.