The influence of prehypertension, hypertension, and glycated hemoglobin on the development of type 2 diabetes mellitus in prediabetes: the Korean Genome and Epidemiology Study (KoGES)

Advancing diabetes prediction with a progressive self-transfer learning framework for discrete time series data

Although diabetes mellitus is a complex and pervasive disease, most studies to date have focused on individual features, rather than considering the complexities of multivariate, multi-instance, and time-series data. In this study, we developed a novel diabetes prediction model that incorporates these complex data types. We applied advanced techniques of data imputation (bidirectional recurrent imputation for time series; BRITS) and feature selection (the least absolute shrinkage and selection operator; LASSO). Additionally, we utilized self-supervised algorithms and transfer learning to address the common issues with medical datasets, such as irregular data collection and sparsity. We also proposed a novel approach for discrete time-series data preprocessing, utilizing both shifting and rolling time windows and modifying time resolution. Our study evaluated the performance of a progressive self-transfer network for predicting diabetes, which demonstrated a significant improvement in metrics compared to non-progressive and single self-transfer prediction tasks, particularly in AUC, recall, and F1 score. These findings suggest that the proposed approach can mitigate accumulated errors and reflect temporal information, making it an effective tool for accurate diagnosis and disease management. In summary, our study highlights the importance of considering the complexities of multivariate, multi-instance, and time-series data in diabetes prediction.

Predictive performance of triglyceride glucose index (TyG index) to identify glucose status conversion: a 5-year longitudinal cohort study in Chinese pre-diabetes people

OBJECTIVE

Triglyceride glucose index (TyG index) has been recommended as an alternative indicator of insulin resistance. However, the association between TyG and regression from prediabetes to normoglycemia remains to be elucidated.

METHODS

This retrospective cohort study involved 25,248 subjects with prediabetes at baseline conducted from 2010 to 2016. A Cox proportional hazard regression model was designed to evaluate the role of TyG in identifying people at converting from prediabetes to normoglycemia. Cox proportional hazards regression with cubic spline functions and smooth curve fitting was used to dig out the nonlinear relationship between them. Detailed evaluations for TyG were also performed using sensitivity and subgroup analyse.

RESULTS

Among the included prediabetes subjects (n = 25,248), the mean age was 49.27 ± 13.84 years old, and 16,701 (66.15%) were male. The mean TyG was 8.83 ± 0.60. The median follow-up time was 2.96 ± 0.90 years. 11,499 (45.54%) individuals had a final diagnosis of normoglycemia. After adjusting for covariates, TyG was negatively affecting the results of glucose status conversion in prediabetes people (HR 0.895, 95% CI 0.863, 0.928). There was a nonlinear connection between TyG and normoglycemia in prediabetes people, and the inflection point was 8.88. The effect sizes (HR) on the left and right sides of the inflection point were 0.99 (0.93, 1.05) and 0.79 (0.74, 0.85), respectively. Sensitivity analysis confirmed the robustness of these results. Subgroup analysis showed that TyG was more strongly associated with incident glucose status conversion in male, BMI ≥ 25. In contrast, there was a weaker relationship in those with female, BMI < 25.

CONCLUSION

Based on sample of subjects evaluated between 2010 and 2016, TyG index appears to be a promising marker for predicting normoglycemic conversion among prediabetes people in China. This study demonstrates a negative and non-linear association between TyG and glucose status conversion from prediabetes to normoglycemia. TyG is strongly related to glucose status conversion when TyG is above 8.88. From a therapeutic point of view, it is meaningful to maintain TyG levels within the inflection point to 8.88.

Associations Between Modifiable Risk Factors and Changes in Glycemic Status Among Individuals With Prediabetes

OBJECTIVE

To examine the associations between modifiable risk factors and glycemic status changes in individuals with prediabetes.

RESEARCH DESIGN AND METHODS

A total of 10,358 individuals with prediabetes defined by their fasting blood glucose and HbA1c levels from the Health Examinees-Gem study were included in the present study. Modifiable factors, including BMI, abdominal obesity, smoking status, physical activity, alcohol consumption, diet quality, hypertension, and dyslipidemia, were examined to determine their associations with changes in glycemic status during follow-up. In addition, modifiable-factor scores were calculated, and their association with changes in glycemic status was also analyzed.

RESULTS

The median follow-up time for this study was 4 years (range, 1-7 years). BMI ≥25 kg/m2 (adjusted odds ratio [OR] 0.71 [95% CI 0.63-0.79]), abdominal obesity (OR 0.76 [95% CI 0.68-0.86]), heavy drinking (OR 0.74 [95% CI 0.60-0.91]), hypertension (OR 0.71 [95% CI 0.64-0.79]), and dyslipidemia (OR 0.78 [95% CI 0.70-0.85]) were associated with a lower possibility of normoglycemia reversion. BMI ≥25 kg/m2 (OR 1.58 [95% CI 1.29-1.94]), abdominal obesity (OR 1.31 [95% CI 1.11-1.55]), current smoking (OR 1.43 [95% CI 1.07-1.91]), and hypertension (OR 1.26 [95% CI 1.07-1.49]) were associated with a higher probability of type 2 diabetes progression. Having more favorable modifiable factors was also associated with normoglycemia reversion (OR 1.46 [95% CI 1.30-1.64]) and type 2 diabetes progression (OR 0.62 [95% CI 0.49-0.77]).

CONCLUSIONS

More favorable modifiable factors were related to a higher probability of returning to normoglycemia and a lower probability of progression to type 2 diabetes.

Long-Term Visit-To-Visit Blood Pressure Variability and Risk of Diabetes Mellitus in Chinese Population: A Retrospective Population-Based Study

Objectives: To examine the association between visit-to-visit blood pressure variability (BPV) and incident diabetes mellitus (DM) risk in a Chinese population. Methods: Data comes from China Health and Nutrition Survey (n = 15,084). BPV was estimated as the average real variability (ARV) using at least three BP measurements from the year preceding the event and was divided into quartiles. Participants were also categorized into 9 groups on the basis of combinations of systolic BPV (SBPV) and diastolic BPV (DBPV) tertiles. Cox proportional hazards regression models were used. Results: During a median follow-up of 16.8 years, 1,030 (6.8%) participants developed diabetes (incidence rate: 4.65/1,000 person-years). The HRs (95% CIs) for the highest quartile (vs. the lowest quartile) of SBPV and DBPV were 1.60 (1.30-1.97) and 1.37 (1.13-1.67), respectively. Participants with both highest SBPV and DBPV tertile had an ≈89% higher risk of DM (HR, 1.89; 95% CI, 1.47-2.42) compared with those in the both SBPV and DBPV tertile 1 group. Conclusion: Higher SBP ARV and DBP ARV were independently associated with increased risk of incident DM, which was augmented when both presented together.

The association between glycosylated haemoglobin and newly diagnosed hypertension in a non-diabetic Sudanese population: a cross-sectional study

BACKGROUND

Glycosylated haemoglobin (HbA1c) is considered reliable for diagnosing and monitoring diabetes mellitus (DM). It also indicates cardiovascular complications related to DM. However, only a few studies have been conducted on this topic.

METHODS

We conducted a cross-sectional study to investigate the association between newly diagnosed hypertension and HbA1c among non-diabetic Sudanese adults. The sociodemographic characteristics of the participants in the sample were gathered using a questionnaire, and HbA1c was measured using an Ichroma machine.

RESULTS

Three hundred and eighty-four healthy participants were enrolled in this study. The median (interquartile range [IQR]) age was 56.0 (14.0) years, and 72.1% of the participants were female. The median (IQR) body mass index (BMI) was 31.2 (8.7) kg/m². One hundred and fifteen (29.9%) participants presented newly diagnosed hypertension. The results of the multivariate analysis showed that age (adjusted odd ratio [AOR] = 1.03; 95% confidence interval [CI] = 1.01‒1.05); BMI (AOR = 1.09; 95% CI = 1.05‒1.14); HbA1c levels (AOR = 2.18; 95% CI = 1.29‒3.67) was positively associated with newly diagnosed hypertension. For an HbA1c level of 5.0% or more, the sensitivity and specificity of newly diagnosed hypertension were 91.3% and 28.2%, respectively (area under the curve = 0.61; 95% CI = 0.55-0.67; P ˂ 0.001). Participants who presented HbA1c levels of 5.0% or more were found to be at higher risk for newly diagnosed hypertension (AOR = 2.53; 95% CI = 1.14‒5.61).

CONCLUSION

The results of this study indicated a high prevalence of newly diagnosed hypertension, and HbA1c levels were positively associated with newly diagnosed hypertension.

Association of healthy lifestyle including a healthy sleep pattern with incident type 2 diabetes mellitus among individuals with hypertension

BACKGROUND

Evidence is limited regarding the association of healthy lifestyle including sleep pattern with the risk of complicated type 2 diabetes mellitus (T2DM) among patients with hypertension. We aimed to investigate the associations of an overall healthy lifestyle including a healthy sleep pattern with subsequent development of T2DM among participants with hypertension compared to normotension, and to estimate how much of that risk could be prevented.

METHODS

This study examined six lifestyle factors with T2DM cases among hypertension (227,966) and normotension (203,005) and their interaction in the UK Biobank. Low-risk lifestyle factors were defined as standard body mass index (BMI), drinking alcohol in moderation, nonsmoking, engaging in moderate- to vigorous-intensity physical activity, eating a high-quality diet, and maintaining a healthy sleep pattern.

RESULTS

There were 12,403 incident T2DM cases during an average of 8.63 years of follow-up. Compared to those with 0 low-risk lifestyle factors, HRs for those with 5-6 were 0.14 (95% CI 0.10 to 0.19) for hypertensive participants, 0.13 (95% CI 0.08 to 0.19) for normotensive participants, respectively (p_trend < 0.001). 76.93% of hypertensive participants were considerably less likely to develop T2DM if they adhered to five healthy lifestyle practices, increased to 81.14% if they followed 6-factors (with a healthy sleep pattern). Compared with hypertension adults, normotensive people gain more benefits if they stick to six healthy lifestyles [Population attributable risk (PAR%) 83.66%, 95% CI 79.45 to 87.00%, p for interaction = 0.0011].

CONCLUSIONS

Adherence to a healthy lifestyle pattern including a healthy sleep pattern is associated with lower risk of T2DM in hypertensives, and this benefit is even further in normotensives.

Paravertebral Muscles as Indexes of Sarcopenia and Sarcopenic Obesity: Comparison With Imaging and Muscle Function Indexes and Impact on Cardiovascular and Metabolic Disorders

OBJECTIVE. The objectives of this study were to propose the use of the cross-sectional area of paravertebral muscle (PMA) and the ratio of the PMA to the cross-sectional area of visceral fat (PVR) as new indexes of sarcopenia or sarcopenic obesity through comparison with existing indexes and to show the clinical associations of PMA and PVR with hypertension and diabetes. SUBJECTS AND METHODS. A total of 1270 participants (608 men and 662 women; mean [± SD] age, 63.57 ± 6.94 years) were recruited from a community-based population of elderly individuals. PMA and PVR were measured on single-slice abdominal CT images. Pearson correlation was used to evaluate the correlation of PMA and PVR with widely used imaging and muscle function indexes of sarcopenia and sarcopenic obesity. Tertile categories of PMA and PVR were evaluated to investigate associations with risks for hypertension and diabetes in men and women, by use of separate multivariable logistic regression models. RESULTS. PMA was correlated with the cross-sectional area of thigh muscle on CT, appendicular skeletal muscle mass (ASM) on dual-energy x-ray absorptiometry, height-adjusted ASM (calculated as ASM divided by the height in meters squared), and body mass index (BMI)-adjusted ASM (calculated as ASM divided by BMI) (p < .01). PMA was also correlated with hand grip strength and gait speeds (p < .01). PVR was correlated with height-adjusted ASM and BMI-adjusted ASM (p < .01). A high PVR significantly decreased the odds ratios for hypertension and diabetes in the unadjusted model and the model adjusted for age, smoking, and drinking status. The ratio of the cross-sectional area of thigh muscle to the cross-sectional area of visceral fat and the BMI-adjusted ASM produced results similar to those of PVR in terms of the odds ratios for hypertension and diabetes. CONCLUSION. Single-slice abdominal CT can supply PMA and visceral fat information together. PMA and PVR were found to be reliable indexes of sarcopenia and sarcopenic obesity. A high PVR was associated with low risks for hypertension and diabetes.

Hypertension and diabetes mellitus: highlights of a complex relationship

PURPOSE OF REVIEW

Herein, we provide a review of the recent literature on the epidemiological and pathophysiological relationship between hypertension (HTN) and diabetes mellitus, along with prognostic implications and current treatment concepts.

RECENT FINDINGS

Diabetes mellitus affects ∼10% of US adults. The prevalence of HTN in adults with diabetes mellitus was 76.3% or 66.0% based on the definitions used by guidelines. There exist differences among major society guidelines regarding the definition of HTN and target blood pressure (BP) levels. Recent basic and clinical research studies have shed light on pathophysiologic and genetic links between HTN and diabetes mellitus. Randomized controlled trials over the past 5 years have confirmed the favorable BP and cardiovascular risk reduction by antidiabetic agents.

SUMMARY

HTN and diabetes mellitus are 'silent killers' with rising global prevalence. The development of HTN and diabetes mellitus tracks each other over time. The coexistence of both clinical entities synergistically contributes to micro- and macro-vasculopathy along with cardiovascular and all-cause mortality. Various shared mechanisms underlie the pathophysiological relationship between HTN and diabetes mellitus. Moreover, BP reduction with lifestyle interventions and antihypertensive agents is a primary target for reducing cardiovascular risk among patients with HTN and diabetes mellitus.

Visceral adiposity index and longitudinal risk of incident metabolic syndrome: Korean genome and epidemiology study (KoGES)

Available data is insufficient to identify the influence of visceral adiposity assessed by visceral adiposity index (VAI) on incident MetS. This study was to evaluate the association of VAI with incident MetS. In a cohort of Korean genome epidemiology study, 5,807 free of MetS were followed-up for 10 years. They were subdivided into 3 tertile groups according to VAI score. Cox proportional hazard model was used to evaluate the hazard ratios (HRs) and 95% confidential interval (CI) [adjusted HRs (95% CI)] for MetS according to VAI tertiles. Subgroup analyses were conducted for VAI and waist circumference (WC). Receiver operating characteristic (ROC) and area under curve (AUC) analyses were conducted to compare the discriminative ability for Mets among indices. The risk for MetS increased proportionally to VAI tertiles in all participants, which was similarly observed in both men and women. Subgroup analysis indicated that group with high VAI and low WC had the increased risk for MetS (all participants: 2.76 [2.48-3.07], men: 2.77 [2.40-3.19] and women: 2.55 [2.16-3.00]), compared with groups with low VAI and low WC. Group with low VAI and high WC generally had the higher adjusted HRs for MetS than group with the high VAI and low WC. In AUC analyses, WC had the highest discriminative ability for Mets. In conclusion, elevated VAI was significantly associated with the increased long-term risk of MetS. VAI is a useful supplementary to classic anthropometric indices in screening high risk group of MetS.

Body fat percentage, obesity, and their relation to the incidental risk of hypertension

Studies have indicated that increased body fat is associated with cardiovascular risk factors including hypertension. However, there is only limited information about the influence of body fat percentage (BF%) on incident hypertension. In a cohort of Korean genome epidemiology study (KoGES), 4864 non-hypertensive participants were divided into 5 quintile groups, and followed-up for 10 years to monitor incident hypertension. Cox proportional hazard model was used to evaluate the hazard ratio (HRs) and 95% confidence interval (CI) for hypertension (adjusted HRs [95% CI]) according to BF% quintile groups. Subgroup analysis was conducted by low or high level of BF% (cutoff: 22.5% in men and 32.5% in women) and low or high level of body mass index (BMI), waist circumference (WC) and waist-to-hip ratio (WHR). In adjusted model, compared with BF% quintile 1, the risk of incident hypertension significantly increased over BF% quintile 3 (BF% ≥19.9%) in men (quintile 3:1.42 [1.10-1.85], quintile 4:1.58 [1.22-2.05], quintile 5:1.82 [1.40-2.36]), and quintile 4 (BF% ≥32.5%) in women (quintile 4:1.48 [1.12-1.94], quintile 5:1.56 [1.20-2.04]). Subgroup analysis showed that individuals with high BF% were significantly associated with the increased risk of hypertension even in individuals with low BMI, WC, and WHR. The risk of hypertension increased proportionally to BF% over the specific level of BF% in Koreans. Even in non-obese individuals, increase in BF% was significantly associated with the increased risk of hypertension.

The association between metabolic syndrome and peanuts, pine nuts, almonds consumption: The Ansan and Ansung Study

BACKGROUND

Previous studies reported an inverted relationship between nut consumption and the incidence of metabolic syndrome (MetS). The present study investigated the incidental risk for MetS according to peanut, almond, and fine nut consumption in the Korean population.

METHODS

In a community-based Korean cohort, 5306 Korean adults were divided into four groups according to their peanut, almond, and fine nut intake (<1/month, 1/month-0.5/week, 0.5-1/week, and ≥1/week, in which one serving = 15 g) and were followed-up for 10 years. A Cox proportional hazard model was used to evaluate the hazard ratios (HRs) with confidence intervals (CI) for MetS in each study group. Age subgroup (≥50 or <50 years) analysis was also conducted.

RESULTS

The age and multivariable-adjusted HRs with 95% CIs for MetS showed a significant inverse dose-response relationship between peanut, almond, and fine nut intake and the incidence of MetS in men and women (multivariable-adjusted HRs [95% CI] in men; 0.91 [0.76-1.09] in 1/month-0.5/week, 1.03 [0.80-1.31] in 0.5-1/week, 0.72 [0.56-0.93] in ≥1/week and in women; 0.81 [0.65-1.003] in 1/month-0.5/week, 0.76 [0.54-1.07] in 0.5-1/week, 0.57 [0.41-0.79] ≥1/week)). Subgroup analysis showed a significant difference in middle-aged men (≥1/week) and old-aged women (≥0.5/week).

CONCLUSION

The results of the present study suggested that peanut, almond, and fine nut intake (≥15 g/week) may be inversely related to incidence risk of MetS in the Korean general population. Additionally, the association between nut consumption and MetS incidence risk may differ in sex and age subgroups.

Levels of Systolic and Diastolic Blood Pressure and Their Relation to Incident Metabolic Syndrome

Background: Elevated blood pressure (BP) is a component of the metabolic syndrome (MetS), and one third of individuals with hypertension simultaneously have MetS. However, the evidence is still unclear regarding the predictive ability of BP for incident MetS. Methods: In total, 5,809 Koreans without baseline MetS were grouped by baseline systolic (SBP) and diastolic BP (DBP) and monitored for 10 years to identify incident MetS. A Cox proportional hazards model was used to evaluate the HR and 95% CI for MetS according to SBP and DBP. Subgroup analysis was conducted in the normotensive population based on a new guideline of the American College of Cardiology and the American Heart Association. Results: High-BP groups tended to have worse metabolic profiles than the lowest-BP group in both SBP and DBP categories. In all of the participants, elevated SBP and DBP levels were significantly associated with the increased HR for MetS, even after adjusting for covariates. Subgroup analysis for normotensive participants indicated that the HR for MetS increased proportionally to both SBP (<110 mm Hg: reference, 110–119 mm Hg: HR = 1.60 [95% CI 1.40–1.84], and 120–129 mm Hg: HR = 2.12 [95% CI 1.82–2.48]) and DBP levels (<70 mm Hg: reference, 71–74 mm Hg: HR = 1.31 [95% CI 1.09–1.58], and 75–79 mm Hg: HR = 1.51 [95% CI 1.25–1.81]). Conclusion: The risk of incident MetS increased proportionally to baseline SBP and DBP, and this was identically observed even in normotensive participants.

Association of fasting glucose and glycated hemoglobin with the long-term risk of incident metabolic syndrome: Korean Genome and Epidemiology Study (KoGES)

AIMS

Previous studies have proposed potential benefit of glycated hemoglobin (HbA1c) supplementary to fasting glucose in detecting metabolic syndrome (MetS). This study was to investigate an association of incident MetS with levels of HbA1c and fasting glucose.

METHODS

In a cohort of Korean Genome and Epidemiology Study, 5515 non-diabetic adults were grouped by the levels of baseline fasting glucose and HbA1c, and followed-up for 10 years. Using multivariate Cox proportional hazards assumption, hazards ratios (HRs) and 95% confidence interval (CI) for incident MetS (adjusted HRs [95% CI]) were calculated according to baseline fasting glucose and HbA1c. In individuals with normal fasting glucose, subgroup analysis was conducted to evaluate an association of HbA1c levels with MetS.

RESULTS

The risk for MetS significantly increased proportionally to fasting glucose ≥ 80 mg/dL and HbA1c ≥ 5.5%, compared with fating glucose < 80 mg/dL and HbA1c < 5.3%, respectively. In subgroups of normal fasting glucose, HbA1c ≥ 5.7% had the increased risk of MetS in fasting glucose < 80 mg/dL (5.7-5.9%: 1.41 [1.07-1.86] and 6.0-6.4%: 2.20 [1.40-2.92]), and HbA1c ≥ 5.5% had the increased risk of MetS in fasting glucose of 80-99 mg/dL (5.5-5.6%: 1.33 [1.08-1.64], 5.7-5.9%: 1.57 (1.27-1.93), and 6.0-6.4%: 2.37 [1.87-3.00]).

CONCLUSIONS

Both elevated fasting glucose and HbA1c were significantly associated with the increased risk of MetS even within normal range. HbA1c is effective in identifying high-risk group for MetS in individuals with normal fasting glucose.

Development of type 2 diabetes mellitus in people with intermediate hyperglycaemia

BACKGROUND

Intermediate hyperglycaemia (IH) is characterised by one or more measurements of elevated blood glucose concentrations, such as impaired fasting glucose (IFG), impaired glucose tolerance (IGT) and elevated glycosylated haemoglobin A1c (HbA1c). These levels are higher than normal but below the diagnostic threshold for type 2 diabetes mellitus (T2DM). The reduced threshold of 5.6 mmol/L (100 mg/dL) fasting plasma glucose (FPG) for defining IFG, introduced by the American Diabetes Association (ADA) in 2003, substantially increased the prevalence of IFG. Likewise, the lowering of the HbA1c threshold from 6.0% to 5.7% by the ADA in 2010 could potentially have significant medical, public health and socioeconomic impacts.

OBJECTIVES

To assess the overall prognosis of people with IH for developing T2DM, regression from IH to normoglycaemia and the difference in T2DM incidence in people with IH versus people with normoglycaemia.

SEARCH METHODS

We searched MEDLINE, Embase, ClincialTrials.gov and the International Clinical Trials Registry Platform (ICTRP) Search Portal up to December 2016 and updated the MEDLINE search in February 2018. We used several complementary search methods in addition to a Boolean search based on analytical text mining.

SELECTION CRITERIA

We included prospective cohort studies investigating the development of T2DM in people with IH. We used standard definitions of IH as described by the ADA or World Health Organization (WHO). We excluded intervention trials and studies on cohorts with additional comorbidities at baseline, studies with missing data on the transition from IH to T2DM, and studies where T2DM incidence was evaluated by documents or self-report only.

DATA COLLECTION AND ANALYSIS

One review author extracted study characteristics, and a second author checked the extracted data. We used a tailored version of the Quality In Prognosis Studies (QUIPS) tool for assessing risk of bias. We pooled incidence and incidence rate ratios (IRR) using a random-effects model to account for between-study heterogeneity. To meta-analyse incidence data, we used a method for pooling proportions. For hazard ratios (HR) and odds ratios (OR) of IH versus normoglycaemia, reported with 95% confidence intervals (CI), we obtained standard errors from these CIs and performed random-effects meta-analyses using the generic inverse-variance method. We used multivariable HRs and the model with the greatest number of covariates. We evaluated the certainty of the evidence with an adapted version of the GRADE framework.

MAIN RESULTS

We included 103 prospective cohort studies. The studies mainly defined IH by IFG5.6 (FPG mmol/L 5.6 to 6.9 mmol/L or 100 mg/dL to 125 mg/dL), IFG6.1 (FPG 6.1 mmol/L to 6.9 mmol/L or 110 mg/dL to 125 mg/dL), IGT (plasma glucose 7.8 mmol/L to 11.1 mmol/L or 140 mg/dL to 199 mg/dL two hours after a 75 g glucose load on the oral glucose tolerance test, combined IFG and IGT (IFG/IGT), and elevated HbA1c (HbA1c5.7: HbA1c 5.7% to 6.4% or 39 mmol/mol to 46 mmol/mol; HbA1c6.0: HbA1c 6.0% to 6.4% or 42 mmol/mol to 46 mmol/mol). The follow-up period ranged from 1 to 24 years. Ninety-three studies evaluated the overall prognosis of people with IH measured by cumulative T2DM incidence, and 52 studies evaluated glycaemic status as a prognostic factor for T2DM by comparing a cohort with IH to a cohort with normoglycaemia. Participants were of Australian, European or North American origin in 41 studies; Latin American in 7; Asian or Middle Eastern in 50; and Islanders or American Indians in 5. Six studies included children and/or adolescents.Cumulative incidence of T2DM associated with IFG5.6, IFG6.1, IGT and the combination of IFG/IGT increased with length of follow-up. Cumulative incidence was highest with IFG/IGT, followed by IGT, IFG6.1 and IFG5.6. Limited data showed a higher T2DM incidence associated with HbA1c6.0 compared to HbA1c5.7. We rated the evidence for overall prognosis as of moderate certainty because of imprecision (wide CIs in most studies). In the 47 studies reporting restitution of normoglycaemia, regression ranged from 33% to 59% within one to five years follow-up, and from 17% to 42% for 6 to 11 years of follow-up (moderate-certainty evidence).Studies evaluating the prognostic effect of IH versus normoglycaemia reported different effect measures (HRs, IRRs and ORs). Overall, the effect measures all indicated an elevated risk of T2DM at 1 to 24 years of follow-up. Taking into account the long-term follow-up of cohort studies, estimation of HRs for time-dependent events like T2DM incidence appeared most reliable. The pooled HR and the number of studies and participants for different IH definitions as compared to normoglycaemia were: IFG5.6: HR 4.32 (95% CI 2.61 to 7.12), 8 studies, 9017 participants; IFG6.1: HR 5.47 (95% CI 3.50 to 8.54), 9 studies, 2818 participants; IGT: HR 3.61 (95% CI 2.31 to 5.64), 5 studies, 4010 participants; IFG and IGT: HR 6.90 (95% CI 4.15 to 11.45), 5 studies, 1038 participants; HbA1c5.7: HR 5.55 (95% CI 2.77 to 11.12), 4 studies, 5223 participants; HbA1c6.0: HR 10.10 (95% CI 3.59 to 28.43), 6 studies, 4532 participants. In subgroup analyses, there was no clear pattern of differences between geographic regions. We downgraded the evidence for the prognostic effect of IH versus normoglycaemia to low-certainty evidence due to study limitations because many studies did not adequately adjust for confounders. Imprecision and inconsistency required further downgrading due to wide 95% CIs and wide 95% prediction intervals (sometimes ranging from negative to positive prognostic factor to outcome associations), respectively.This evidence is up to date as of 26 February 2018.

AUTHORS' CONCLUSIONS

Overall prognosis of people with IH worsened over time. T2DM cumulative incidence generally increased over the course of follow-up but varied with IH definition. Regression from IH to normoglycaemia decreased over time but was observed even after 11 years of follow-up. The risk of developing T2DM when comparing IH with normoglycaemia at baseline varied by IH definition. Taking into consideration the uncertainty of the available evidence, as well as the fluctuating stages of normoglycaemia, IH and T2DM, which may transition from one stage to another in both directions even after years of follow-up, practitioners should be careful about the potential implications of any active intervention for people 'diagnosed' with IH.