Risk factors for incident type 2 diabetes in individuals with a BMI of <27 kg/m2: the role of gamma-glutamyltransferase. Data from an Epidemiological Study on the Insulin Resistance Syndrome (DESIR)

Incidence and temporal trends in type 2 diabetes by weight status: A systematic review and meta-analysis of prospective cohort studies

Background

Diabetes is more prevalent among overweight/obese individuals, but has become a significant public health challenge among normal weight populations. In this meta-analysis, we aimed to estimate diabetes/prediabetes incidence and its temporal trends by weight status.

Methods

PubMed, Embase, Web of Science, and Cochrane Library were searched until 8 December 2021. Prospective cohort studies reporting diabetes incidence by baseline body mass index (BMI) categories in adults were included. The median year of data collection was used to assess the temporal trends. Subgroup analyses and meta-regression were also performed.

Results

We included 94 studies involving 3.4 million adults from 22 countries. The pooled diabetes incidence in underweight, normal-weight, and overweight/obese adults was 4.5 (95% confidence interval (CI) = 2.8-7.3), 2.7 (95% CI = 2.2-3.3), and 10.5 (95% CI = 9.3-11.8) per 1000 person-years, respectively. The diabetes incidence in low- and middle-income countries (LMICs) was higher than in high-income countries among normal-weight (5.8 vs 2.0 per 1000 person-years) or overweight/obese (15.9 vs 8.9 per 1000 person-years) adults. European and American regions had a higher diabetes incidence than the non-Western areas, regardless of weight status. Underweight diabetes incidence decreased significantly from 1995-2000 to 2005-2010. Diabetes incidence in normal-weight populations has increased continuously since 1985 by an estimated 36% every five years. In overweight/obese adults, diabetes incidence increased between 1985-1990 and 1995-2000, stabilised between 2000 and 2010, and spiked suddenly after 2010.

Conclusions

Diabetes incidence and its temporal trends differed by weight status. The continuous upward trend of diabetes incidence among overweight/obese individuals requires urgent attention, particularly in LMICs. Furthermore, diabetes among normal-weight individuals is becoming a significant public health problem.

Registration

PROSPERO (CRD42020215957).

Evidence-based European recommendations for the dietary management of diabetes

Diabetes management relies on effective evidence-based advice that informs and empowers individuals to manage their health. Alongside other cornerstones of diabetes management, dietary advice has the potential to improve glycaemic levels, reduce risk of diabetes complications and improve health-related quality of life. We have updated the 2004 recommendations for the nutritional management of diabetes to provide health professionals with evidence-based guidelines to inform discussions with patients on diabetes management, including type 2 diabetes prevention and remission. To provide this update we commissioned new systematic reviews and meta-analyses on key topics, and drew on the broader evidence available. We have strengthened and expanded on the previous recommendations to include advice relating to dietary patterns, environmental sustainability, food processing, patient support and remission of type 2 diabetes. We have used the Grading of Recommendations, Assessment, Development and Evaluations (GRADE) approach to determine the certainty of evidence for each recommendation based on findings from the commissioned and identified systematic reviews. Our findings indicate that a range of foods and dietary patterns are suitable for diabetes management, with key recommendations for people with diabetes being largely similar for those for the general population. Important messages are to consume minimally processed plant foods, such as whole grains, vegetables, whole fruit, legumes, nuts, seeds and non-hydrogenated non-tropical vegetable oils, while minimising the consumption of red and processed meats, sodium, sugar-sweetened beverages and refined grains. The updated recommendations reflect the current evidence base and, if adhered to, will improve patient outcomes.

Role of Liver Enzymes in the Relationship Between Particulate Matter Exposure and Diabetes Risk: A Longitudinal Cohort Study

CONTEXT

Particulate matter (PM) is an important risk factor for diabetes. However, its underlying mechanisms remain poorly understood. Although liver-derived biological intermediates may play irreplaceable roles in the pathophysiology of diabetes, few studies have explored this in the association between PM and diabetes.

OBJECTIVE

We investigated the role of liver enzymes in mediating the relationship between PM exposure and diabetes.

METHODS

We included a total of 7963 participants from the China Multi-Ethnic Cohort. Residential exposure to PM was assessed using a validated spatial-temporal assessment method. Diabetes was diagnosed according to the criteria from American Diabetes Association. Associations between PM, liver enzyme [including alanine aminotransferase (ALT), aspartate aminotransferase, alkaline phosphatase, and γ-glutamyl transpeptidase (GGT)], and diabetes were estimated using multivariable regression models. The function of liver enzymes in the relationship between PM and diabetes was assessed using mediation analysis.

RESULTS

PM exposure was positively associated with the odds of diabetes, with odds ratios of 1.32 (95% CI 0.83, 2.09), 1.33 (95% CI 1.07, 1.65), and 1.18 (95% CI 1.02, 1.36) for every 10-μg/m3 increment in ≤1 μm (PM1), ≤2.5 μm (PM2.5), and ≤10 μm (PM10) PM, respectively. ALT (4.47%) and GGT (4.78%) exhibited statistically significant mediation effects on the association between PM2.5 and diabetes, and the ALT (4.30%) also had a mediating role on PM10. However, none of the liver enzymes had a significant mediating effect on PM1.

CONCLUSION

The relationship between PM and diabetes is partially mediated by liver enzymes, suggesting that lipid accumulation, oxidative stress, and chronic inflammation in the liver may be involved in its pathogenesis.

Does NAFLD mediate the relationship between obesity and type 2 diabetes risk? evidence from the multi-ethnic study of atherosclerosis (MESA)

PURPOSE

To estimate the effect of obesity on type 2 diabetes (T2DM) risk and evaluate to what extent non-alcoholic fatty liver disease (NAFLD) mediates this association.

METHODS

Data came from 4,522 adults ages 45-84 participating in the Multi-Ethnic Study of Atherosclerosis cohort. Baseline obesity was defined using established BMI categories. NAFLD was measured by CT scans at baseline and incident T2DM defined as fasting glucose ≥126 mg/dL or use of diabetes medications.

RESULTS

Over a median 9.1 years of follow-up between 2000 and 2012, 557 new cases of T2DM occurred. After adjusting for age, sex, race/ethnicity, education, diet and exercise, those with obesity had 4.5 times the risk of T2DM compared to normal weight (hazard ratio [HR] = 4.5, 95% confidence interval [CI]: 3.0, 5.9). The mediation analysis suggested that NAFLD accounted for ~36% (95% CI: 27, 44) of the effect (direct effect HR = 3.2, 95% CI: 2.3, 4.6; indirect effect through NAFLD, HR = 1.4, 95% CI: 1.3, 1.5).

CONCLUSIONS

These data suggest that the association between obesity and T2DM risk is partially explained by the presence of NAFLD. Future studies should evaluate if NAFLD could be an effective target to reduce the effect of obesity on T2DM.

Influences of pregravid liver enzyme levels on the development of gestational diabetes mellitus

BACKGROUND & AIMS

Elevated liver enzymes are associated with later development of type 2 diabetes mellitus. The objective of this study was to assess the association between prepregnancy liver enzyme levels and subsequent risk of gestational diabetes mellitus.

METHODS

Data from a total of 236,109 women who participated in the National Health Screening Examination between 2011 and 2015 was analysed. Multivariate logistic regression analyses were performed to estimate the risk of developing gestational diabetes mellitus in relation to pregravid liver enzyme levels. Subgroup analyses were performed according to pregravid obesity and metabolic syndrome (MetS).

RESULTS

Approximately 5.7% and 1.1% of women developed gestational diabetes mellitus with and without insulin treatment requirement respectively. Pregravid gamma-glutamyl transferase and alanine aminotransferase levels with greater than or equal to the 4th quartile were associated with significantly increased risks of gestational diabetes mellitus requiring insulin treatment in women with obesity and with MetS, (odds ratios [ORs] with 6.228 and 9.505, respectively, P < .001 for both). In women without obesity and without MetS, the risks of gestational diabetes mellitus requiring insulin treatment were also significant (ORs with 2.837 and 3.029, respectively, P < .001 for both). The elevated pregravid liver enzymes were associated with gestational diabetes mellitus without insulin treatment requirement, but minimally.

CONCLUSIONS/INTERPRETATION

The elevated pregravid liver enzyme levels were significantly associated with the subsequent risk of gestational diabetes mellitus, especially gestational diabetes mellitus requiring insulin treatment, not only in women with obesity or MetS, but also in women without obesity or MetS.

Association of liver enzymes levels with fasting plasma glucose levels in Southern China: a cross-sectional study

OBJECTIVE

According to several studies, liver enzymes levels are associated with fasting plasma glucose (FPG) levels. However, the association stratified by body mass index (BMI) remains to be elucidated, especially in Southern China. Therefore, the aim of this study was to investigate the correlation between liver enzymes levels and FPG levels stratified by BMI in Southern China.

DESIGN

Cross-sectional study.

PARTICIPANTS AND SETTING

3056 individuals participated in real-time interviews and blood tests in Southern China. Participants were divided into three groups (underweight, normal weight and overweight or obesity) based on BMI cut-offs.

MAIN OUTCOME MEASURED

Partial correlation analysis was performed to investigate the relationship between FPG levels and liver tests. Multivariate logistic regression analyses were applied to calculate the adjusted ORs for FPG levels based on liver enzymes levels.

RESULTS

There was no association between liver enzymes and FPG either in the underweight group or in the normal weight group; however, a significant correlation was observed in the overweight or obesity group (alanine transaminase (ALT), p<0.01; aspartate aminotransferase (AST), p<0.05). After adjusting for confounding factors, the highest tertiles of ALT still remained significantly positively related to FPG levels in the overweight or obesity group, with an OR of 2.205 (95% CI 1.442 to 3.371) for the 5.56≤FPG<7.00 mmol/L vs the FPG<5.56 mmol/L group and with an OR of 2.297 (95% CI 1.017 to 5.187) for the FPG≥7.00 mmol/L vs the FPG<5.56 mmol/L group, but this correlation was not found for AST.

CONCLUSIONS

The association of liver enzymes levels with FPG levels differed based on different BMI cut-offs. ALT levels were significantly positively associated with FPG levels in the overweight or obesity group, but not in the other two groups; AST levels were not associated with FPG levels in any group.

Non-alcoholic fatty liver disease: Prevalence and all-cause mortality according to sedentary behaviour and cardiorespiratory fitness. The HUNT Study

PURPOSE

Sedentary behaviour (SB) and low physical activity (PA) are independently associated with non-alcoholic fatty liver disease (NAFLD). Compared to PA, high cardiorespiratory fitness (CRF) has been associated with a higher protection against all-cause mortality and a number of specific diseases. However, this relationship has not been investigated in NAFLD. This study examined the roles of SB and CRF on: i) the likelihood of having NAFLD in the general population, and ii) the risk of mortality over 9 years within individuals having NAFLD.

METHODS

A cross-sectional analysis of 15,781 adults (52% female; age range 19-95 years) was conducted. Self-reported SB was divided into tertiles. CRF was estimated using validated non-exercise models, and the presence of NAFLD from the Fatty Liver Index. Adjusted Odds Ratios and 95% Confidence Intervals for NAFLD were estimated using logistic regression analyses. Hazard Ratios for all-cause mortality were estimated using Cox proportional hazard regression in individuals with NAFLD.

RESULTS

For each additional 1 h/d of SB, the likelihood of having NAFLD was significantly increased by 4% (CI, 3-6%). In combined analyses, compared with the reference group [high CRF and low (≤4 h/d) SB], individuals with low CRF had a markedly higher likelihood of having NAFLD (OR, 16.9; CI 12.9-22.3), even if they had SB ≤ 4 h/d. High CRF attenuated the negative role of SB up to 7 h/d on NAFLD. Over 9.4 ± 1.3 years of follow-up, individuals with NAFLD and low CRF had the risk of mortality increased by 52% (CI, 10-106%) compared to those with high CRF, regardless of SB or meeting PA guidelines.

CONCLUSIONS

Low CRF increases the risk of premature death in individuals with NAFLD, and is strongly associated with higher likelihood of having NAFLD, outweighing the influence of SB.

Higher level of GGT during mid-pregnancy is associated with increased risk of gestational diabetes mellitus

OBJECTIVE

This study was to explore the link between gamma-glutamyl transferase (GGT), alanine transaminase (ALT) and aspartate transaminase (AST) levels during early-middle pregnancy and subsequent risk of gestational diabetes mellitus (GDM).

METHODS

In a prospective cohort study, pregnant women enrolled prior to 16 weeks of gestation were followed up until delivery. GGT, AST and ALT levels were tested during weeks 14-18 of gestation and oral glucose tolerance test was conducted during 24-28 weeks to screen GDM.

RESULTS

The GDM rate was 8.1% (122/1512). Mean GGT level was higher in GDM than non-GDM women (18.7 ± 13.0 vs 14.5 ± 7.0, P < .001). The higher GGT level was 26.9~74.0 U/L, which was significantly associated with increased risk of GDM. The adjusted RR (95% CI) comparing higher GGT level versus lower was 5.40 (3.36-8.68). No significant correlation was found between ALT or AST levels and the risk of GDM.

CONCLUSIONS

The results suggest that pregnant women with higher serum GGT during early-middle pregnancy have higher risk of developing GDM. A GGT level >26.9 U/L may indicate an increased risk of developing GDM later and should be further concerned.

Gamma-glutamyltransferase, fatty liver index and hepatic insulin resistance are associated with incident hypertension in two longitudinal studies

OBJECTIVE

We hypothesized that liver markers and the fatty liver index (FLI) are predictive of incident hypertension and that hepatic insulin resistance plays a role.

METHODS

The association between liver markers and incident hypertension was analysed in two longitudinal studies of normotensive individuals, 2565 from the 9-year data from an epidemiological study on the insulin resistance cohort and the 321 from the 3-year 'Relationship between Insulin Sensitivity and Cardiovascular disease' cohort who had a measure of endogenous glucose production. The FLI is calculated from BMI, waist circumference, triglycerides and gamma-glutamyltransferase (GGT) and the hepatic insulin resistance index from endogenous glucose production and fasting insulin.

RESULTS

The incidence of hypertension increased across the quartiles groups of both baseline GGT and alanine aminotransferase. After adjustment for sex, age, waist circumference, fasting glucose, smoking and alcohol intake, only GGT was significantly related with incident hypertension [standardized odds ratio: 1.21; 95% confidence interval (1.10-1.34); P = 0.0001]. The change in GGT levels over the follow-up was also related with an increased risk of hypertension, independently of changes in body weight. FLI analysed as a continuous value, or FLI at least 60 at baseline were predictive of incident hypertension in the multivariable model. In the RISC cohort, the hepatic insulin resistance index was positively related with the risk of 3-year incident hypertension [standardized odds ratio: 1.54 (1.07-2.22); P = 0.02].

CONCLUSION

Baseline GGT and FLI, as well as an increase in GGT over time, were associated with the risk of incident hypertension. Enhanced hepatic insulin resistance predicted the onset of hypertension and may be a link between liver markers and hypertension.

Inverse Relationship between Hepatic Steatosis and Alanine Aminotransferase with Sex Hormone-Binding Globulin in Men

PURPOSE

Sex hormone-binding globulin (SHBG) is a serum glycoprotein produced predominantly in hepatocytes. As such, the synthesis of SHBG could be associated with liver function and metabolic syndrome. Alanine aminotransferase (ALT) levels could reflect hepatocellular injury and insulin resistance; however, the relationship between hepatic steatosis and ALT with SHBG has not been investigated in humans. The objective of this study was to investigate the associations between SHBG and hepatocyte damage among Korean male patients with hepatic steatosis enrolled in a health examination program.

MATERIALS AND METHODS

We performed a retrospective cross-sectional study with 922 participants who underwent routine health examinations. A total of 922 men with or without hepatic steatosis were divided into three groups. We analyzed the risk of lower serum SHBG levels with or without elevated serum ALT levels using odds ratios with 95% confidence intervals (CIs).

RESULTS

A significantly increased risk of lower serum SHBG level was observed in the group with hepatic steatosis and ALT elevation (95% CI 1.591-4.681).

CONCLUSION

In men with hepatic steatosis, we found that elevated serum ALT levels were associated with lower serum SHBG levels. This finding suggests that subjects with both hepatic steatosis and increased ALT should be considered to have low levels of SHBG.

Gamma-Glutamyltransferase: A Predictive Biomarker of Cellular Antioxidant Inadequacy and Disease Risk

Gamma-glutamyltransferase (GGT) is a well-established serum marker for alcohol-related liver disease. However, GGT's predictive utility applies well beyond liver disease: elevated GGT is linked to increased risk to a multitude of diseases and conditions, including cardiovascular disease, diabetes, metabolic syndrome (MetS), and all-cause mortality. The literature from multiple population groups worldwide consistently shows strong predictive power for GGT, even across different gender and ethnic categories. Here, we examine the relationship of GGT to other serum markers such as serum ferritin (SF) levels, and we suggest a link to exposure to environmental and endogenous toxins, resulting in oxidative and nitrosative stress. We observe a general upward trend in population levels of GGT over time, particularly in the US and Korea. Since the late 1970s, both GGT and incident MetS and its related disorders have risen in virtual lockstep. GGT is an early predictive marker for atherosclerosis, heart failure, arterial stiffness and plaque, gestational diabetes, and various liver diseases, including viral hepatitis, other infectious diseases, and several life-threatening cancers. We review literature both from the medical sciences and from life insurance industries demonstrating that serum GGT is a superior marker for future disease risk, when compared against multiple other known mortality risk factors.

Characterization of metabolically unhealthy normal-weight individuals: Risk factors and their associations with type 2 diabetes

OBJECTIVE

A proportion of type 2 diabetes cases arise from normal-weight individuals who can therefore be considered to be "metabolically unhealthy normal-weight" (MUH-NW). It remains unclear which factors account for this access risk. Our aims were to identify risk factors for type 2 diabetes in normal-weight individuals and to compare the strengths of their associations with type 2 diabetes to that observed in overweight and obese participants.

METHODS

A case-cohort, including 2027 sub-cohort participants and 706 incident type 2 cases, was designed within the population-based European Prospective Investigation into Cancer and Nutrition Potsdam study. Adjusted means and relative frequencies of anthropometric, lifestyle and biochemical risk factors were calculated in groups stratified by BMI and incident diabetes status. Cox regressions were applied to evaluate associations between these variables and diabetes risk stratified by BMI category.

RESULTS

MUH-NW individuals were characterized by known diabetes risk factors, e.g. they were significantly more likely to be male, former smokers, hypertensive, and less physically active compared to normal-weight individuals without incident diabetes. Higher waist circumference (women: 75.5 vs. 73.1cm; men: 88.0 vs. 85.1cm), higher HbA1c (6.1 vs. 5.3%), higher triglycerides (1.47 vs. 1.11 mmol/l), and higher levels of high sensitive C-reactive protein (0.81 vs. 0.51 mg/l) as well as lower levels of HDL-cholesterol (1.28 vs. 1.49 mmol/l) and adiponectin (6.32 vs. 8.25 μg/ml) characterized this phenotype. Stronger associations with diabetes among normal-weight participants compared to overweight and obese (p for interaction<0.05) were observed for height, waist circumference, former smoking, and hypertension.

CONCLUSIONS

Normal-weight individuals who develop diabetes have higher levels of diabetes risk factors, however, frequently still among the normal range. Still, hypertension, elevated HbA1c and lifestyle risk factors might be useful indicators of risk.

Serum gamma-glutamyltransferase is associated with impaired fasting glucose in Chinese adults: the Cardiometabolic Risk in Chinese (CRC) study

Recently, several studies found raised serum γ-glutamyltransferase (GGT), and traditional marker of liver damage was associated with the risk of type 2 diabetes. The purpose of this study was to investigate the relationship between GGT and impaired fasting glucose (IFG), and evaluate the modification effects of age, BMI, prehypertension, and lipids in a large sample of Chinese adults. The study samples are from a community-based health examination survey in China. The sample for our analysis included 7,309 participants. IFG was defined as FBG from 6.1 to 7.0 mmol/L. Serum GGT, lipids, blood pressure, and glucose were measured. The odds ratios (ORs, 95 % CI) of IFG across increasing quintiles of GGT were 1.00, 0.91 (0.49-1.72), 1.27 (0.68-2.38), 2.31 (1.29-4.15), and 2.42 (1.32-4.42) (P for trend < 0.0001), adjusting for age, sex, BMI, blood pressure, glucose, and lipids. We found significant interactions between age, BMI, and GGT on IFG risk. When the joint effects were examined, we found an additional effect of triglycerides (TG) and GGT levels on IFG. Our data indicate that serum GGT concentration was associated with the risk of IFG, and the association was modified by TG level.

Increased liver markers are associated with higher risk of type 2 diabetes

AIM: To investigate the association between liver markers and the risk of type 2 diabetes (T2DM) and impaired fasting glucose (IFG).

METHODS: A total of 8863 participants (3408 men and 5455 women) over 30 years of age were analyzed from the fifth Korean National Health and Nutrition Examination Survey (2010-2011). The associations of serum liver markers such as aspartate aminotransferase (AST), alanine aminotransferase (ALT), AST/ALT, and gamma-glutamyltransferase (GGT) with T2DM and IFG were analyzed using logistic regression models. Participants were divided into sex-specific quartiles on the basis of liver markers.

RESULTS: The prevalence of T2DM and IFG were 11.3% and 18.3%. Increasing quartiles of ALT and GGT were positively and AST/ALT were negatively correlated with T2DM and IFG. Analysis of the liver marker combinations showed that if any two or more markers were in the highest risk quartile, the risks of both T2DM and IFG increased significantly. The risk was greatest when the highest ALT and GGT and lowest AST/ALT quartile were combined, with the risk of T2DM at 3.21 (95%CI: 1.829-5.622, P < 0.001) in men and 4.60 (95%CI: 3.217-6.582, P < 0.001) in women. Men and women with the highest AST and ALT and lowest AST/ALT quartile had a 1.99 and 2.40 times increased risk of IFG.

CONCLUSION: Higher levels of GGT and ALT and lower AST/ALT within the physiological range are independent, additive risk factors of T2DM and IFG.

Implication of corticotropic hormone axis in eating behaviour pattern in obese and type 2 diabetic participants

In Algeria, eating behaviour has been increasingly deviated from its traditional Mediterranean diet to modern fast food style. The present study examines the interactions between eating behaviour pattern (EBP), corticotropic hormone axis and the metabolic syndrome. Our Algerian population cohort comprised of 410 participants (130 obese, 170 type 2 diabetics and 110 healthy participants). The EBP was evaluated by the Three-Factor Eating Questionnaire test. The anthropometric and metabolic parameters (glucose, TAG, HDL, LDL and cholesterol) and the concentrations of hormones (insulin, adrenocorticotropin hormone (ACTH), cortisol and growth hormone) were determined by biometrics, spectrophotometry and RIA, respectively. Multivariate analyses showed a high correlation between the EBP and the metabolic syndrome, particularly between insulin-resistant state and hypertrophy of visceral adipose tissue. Compared with healthy participants, obese ones showed the hyperphagic type of EBP, i.e. disinhibition and hunger disorders. Conversely, the diabetics showed both the hypophagic and hyperphagic type of EBP. In diabetic and obese participants, cortisol and ACTH secretions were significantly altered, leading to metabolic disorders. The present study confirms the role of EBP in obesity and diabetes.

Role of sex steroids, intrahepatic fat and liver enzymes in the association between SHBG and metabolic features

BACKGROUND

SHBG and liver enzymes levels are both associated with the risk of type 2 diabetes. However, the relationship between SHBG with liver enzymes and intrahepatic fat content remain poorly understood.

OBJECTIVE

To investigate whether SHBG is correlated with glucose and lipids levels and whether this association depends on fatty liver content, liver enzymes or sex hormone concentrations.

DESIGN AND PATIENTS

We studied 233 dysmetabolic men with measures of plasma SHBG, total testosterone, 17β-oestradiol, glucose, adiponectin, liver enzymes and hepatokines. Intrahepatic liver fat and visceral fat contents were measured by magnetic resonance imaging in 108 of these individuals.

RESULTS

After adjustment for age, SHBG concentration was inversely correlated with fasting glucose (βstandardized  = -0·21, P = 0·0007), HbA1c (βstandardized  = -0·27, P < 0·0001), triglycerides (βstandardized  = -0·19, P = 0·003) and positively correlated with HDL-Cholesterol (βstandardized  = 0·14, P = 0·03). These correlations persisted after adjustment for either total testosterone or 17β-oestradiol levels. SHBG was not related to either fetuin A or FGF 21 concentrations. The inverse association of SHBG with HbA1c and glycaemia was not altered after adjusting for liver markers but was no longer significant after adjustment for hepatic fat content.

CONCLUSION

The significant association between SHBG and fasting glycaemia, HbA1c and lipid levels in dysmetabolic men was not related to either sex hormones or markers of liver function, but was dependent on intrahepatic fat. This suggests that intrahepatic fat, but not alterations in liver function markers, may be involved in the association between SHBG and glucose and lipid metabolism.

The clinical importance of serum γ-glutamyltransferase level as an early predictor of obesity development in Korean men

BACKGROUND AND OBJECTIVE

Serum γ-glutamyl transferase (GGT) levels are known to be positively associated with obesity. We aimed at verifying an association between baseline GGT levels and the development of obesity in Korean men.

PATIENTS AND METHODS

This prospective cohort study was performed on 18,510 initially non-obese Korean men. The total follow-up period was 66,993.3 person years and the average follow-up period was 3.62 years (standard deviation [SD], 1.44). Cox proportional hazards model was used to determine hazard ratios for the risk of obesity development.

RESULTS

We found a strong positive association between serum GGT levels at baseline and obesity development, after adjusting for multiple covariates. The risk of obesity development was found to be significantly and dose-dependently associated with serum GGT level. Moreover, estimated hazard ratios for severe obesity (BMI (body mass index) ≥30 kg/m(2)) attributable to serum GGT levels were much higher than those for obesity (BMI ≥ 25 kg/m(2)). The significant association was also found for WC (waist circumference)-defined obesity (WC > 90 cm).

CONCLUSIONS

Our findings, which were obtained from a large cohort, indicate that serum GGT is an early predictor of obesity development. Furthermore, this association was remained significant after adjusting for multiple baseline covariates.

Adipocytokines, hepatic and inflammatory biomarkers and incidence of type 2 diabetes. the CoLaus study

CONTEXT

There is contradictory information regarding the prognostic importance of adipocytokines, hepatic and inflammatory biomarkers on the incidence of type 2 diabetes. The objective was to assess the prognostic relevance of adipocytokine and inflammatory markers (C-reactive protein - CRP; interleukin-1beta - IL-1β; interleukin-6- IL-6; tumour necrosis factor-α - TNF-α; leptin and adiponectin) and gamma-glutamyl transpeptidase (γGT) on the incidence of type 2 diabetes.

METHODS

Prospective, population-based study including 3,842 non-diabetic participants (43.3% men, age range 35 to 75 years), followed for an average of 5.5 years (2003-2008). The endpoint was the occurrence of type 2 diabetes.

RESULTS

208 participants (5.4%, 66 women) developed type 2 diabetes during follow-up. On univariate analysis, participants who developed type 2 diabetes had significantly higher baseline levels of IL-6, CRP, leptin and γGT, and lower levels of adiponectin than participants who remained free of type 2 diabetes. After adjusting for a validated type 2 diabetes risk score, only the associations with adiponectin: Odds Ratio and (95% confidence interval): 0.97 (0.64-1.47), 0.84 (0.55-1.30) and 0.64 (0.40-1.03) for the second, third and forth gender-specific quartiles respectively, remained significant (P-value for trend = 0.05). Adding each marker to a validated type 2 diabetes risk score (including age, family history of type 2 diabetes, height, waist circumference, resting heart rate, presence of hypertension, HDL cholesterol, triglycerides, fasting glucose and serum uric acid) did not improve the area under the ROC or the net reclassification index; similar findings were obtained when the markers were combined, when the markers were used as continuous (log-transformed) variables or when gender-specific quartiles were used.

CONCLUSION

Decreased adiponectin levels are associated with an increased risk for incident type 2 diabetes, but they seem to add little information regarding the risk of developing type 2 diabetes to a validated risk score.

Gamma-glutamyltransferase, alanine transaminase and aspartate transaminase levels and the diagnosis of gestational diabetes mellitus

OBJECTIVES

To evaluate gamma-glutamyltransferase (GGT), alanine transaminases (ALT) and aspartate transaminases (AST) levels and prevalent gestational diabetes mellitus (GDM).

DESIGN AND METHODS

Random plasma glucose, GGT, ALT and AST and the 50-g glucose challenge test were done on antenatal women followed by diagnostic 3-point 75-g oral glucose tolerance test within two weeks. GDM was diagnosed by ADA (2011) criteria.

RESULTS

The GDM rate was 12.2% (319/2610). Mean GGT level was higher in GDM women, 18 ± 12 vs. 16 ± 11 IU/L; P=0.03. The risk for GDM was higher for women in the highest GGT quartile band compared to the lowest: RR 1.35 95%CI 1.0-1.8; P=0.04. However, after adjustment for confounders, GGT was no longer associated with GDM. There was no correlation between ALT and AST levels and GDM.

CONCLUSIONS

Liver transaminases do not predict GDM in contrast to type 2 diabetes.

Can serum gamma-glutamyltransferase levels be useful at diagnosing gestational diabetes mellitus?

OBJECTIVE

The aim of this study was to evaluate plasma gamma-glutamyltransferase (GGT) in gestational diabetes mellitus (GDM) in pregnant women at oral glucose tolerance test (OGTT) and the diagnosis of GDM and to explore whether this activity is associated with metabolic parameters.

METHOD

This prospective control study included 37 women with GDM and 42 women with normal glucose tolerance in pregnancy (control group). In the study group (GDM), blood was taken for analyzing 100 g OGTT from women who have abnormal 50 g glucose challenge test (GCT).

RESULTS

Compared with the controls, the GDM group had significantly higher mean values for serum fasting glucose, insulin, homeostasis model assessment-insulin resistance (HOMA-IR), triglyceride and GGT. Within the GDM group, GGT levels were only negatively correlated with high-density lipoprotein (r = -0.41, p = 0.01). GGT was determined to be an independent metabolic parameter for GDM. While performing analyses receiver operational curve analysis, GGT cutoff set was set at 16 IU/L, the sensitivity was calculated as 86%, and specificity was as 37%.

CONCLUSION

The increase at GGT level is an independent risk factor for GDM and identified as high-risk women for diagnosis of GDM.

Low water intake and risk for new-onset hyperglycemia

OBJECTIVE

Water intake alters vasopressin secretion. Recent findings reveal an independent association between plasma copeptin, a surrogate for vasopressin, and risk of diabetes.

RESEARCH DESIGN AND METHODS

Participants were 3,615 middle-aged men and women, with normal baseline fasting glycemia (FG), who were recruited in a 9-year follow-up study. Odds ratios (ORs) and 95% CIs for the incidence of hyperglycemia (FG ≥6.1 mmol/L or treatment for diabetes) were calculated according to daily water intake classes based on a self-administered questionnaire.

RESULTS

During follow-up, there were 565 incident cases of hyperglycemia. After adjustment for confounding factors, ORs (95% CIs) for hyperglycemia associated with classes of water intake (<0.5 L, n = 677; 0.5 to <1.0 L, n = 1,754; and >1.0 L, n = 1,184) were 1.00, 0.68 (0.52-0.89), and 0.79 (0.59-1.05), respectively (P = 0.016).

CONCLUSIONS

Self-reported water intake was inversely and independently associated with the risk of developing hyperglycemia.

Liver enzymes are associated with hepatic insulin resistance, insulin secretion, and glucagon concentration in healthy men and women

OBJECTIVE

The pathophysiological mechanisms to explain the association between risk of type 2 diabetes and elevated concentrations of γ-glutamyltransferase (GGT) and alanineaminotransferase (ALT) remain poorly characterized. We explored the association of liver enzymes with peripheral and hepatic insulin resistance, insulin secretion, insulin clearance, and glucagon concentration.

RESEARCH DESIGN AND METHODS

We studied 1,309 nondiabetic individuals from the Relationship between Insulin Sensitivity and Cardiovascular disease (RISC) study; all had a euglycemic-hyperinsulinemic clamp and an oral glucose tolerance test (OGTT) with assessment of insulin secretion and hepatic insulin extraction. The hepatic insulin resistance index was calculated in 393 individuals.

RESULTS

In both men and women, plasma concentrations of GGT and ALT were inversely related with insulin sensitivity (M/I) (all P < 0.01). Likewise, the hepatic insulin resistance index was positively correlated with both GGT (r = 0.37, P < 0.0001, men; r = 0.36, P < 0.0001, women) and ALT (r = 0.25, P = 0.0005, men; r = 0.18, P = 0.01, women). These associations persisted in multivariable models. Increased GGT and ALT were significantly associated with higher insulin secretion rates and with both reduced endogenous clearance of insulin and hepatic insulin extraction during the OGTT (P = 0.0005 in men; P = 0.003 in women). Plasma fasting glucagon levels increased over ALT quartiles (men, quartile 4 vs. quartile 1 11.2 ± 5.1 vs. 9.3 ± 3.8 pmol/L, respectively, P = 0.0002; women, 9.0 ± 4.3 vs. 7.6 ± 3.1, P = 0.001).

CONCLUSIONS

In healthy individuals, increased GGT and ALT were biomarkers of both systemic and hepatic insulin resistance with concomitant increased insulin secretion and decreased hepatic insulin clearance. The novel finding of a positive correlation between ALT and fasting glucagon level concentrations warrants confirmation in type 2 diabetes.

Gamma-glutamyl transferase is strongly associated with degree of overweight and sex

Gamma-glutamyl transferase (GGT) is a marker for cardiovascular risk and an independent predictor of long-term outcome in adults. Epidemiological data from pediatric cohorts are rare. We studied the association of GGT to body mass index as a standard deviation score, sex, and age in 68,415 children (age 11.7 ± 4.4 years; 48% boys; body mass index 27.2 ± 7.4 kg/m2; GGT measured in n = 23,955). GGT >50 U/L is strongly associated with extreme obesity (odds ratio 27.13, 95% confidence interval 15.07-48.85) and male sex (odds ratio 2.60, 95% confidence interval 2.03-3.31). GGT seems to be of clinical relevance and may be marketable as a surrogate in risk profiling for children with obesity.

When should screening be performed for gestational diabetes?

AIM

To consider the arguments for screening outside the standard screening period of 24 to 28 weeks of gestation.

MATERIALS AND METHODS

A search of the literature between 1990 and 2010 was performed using the PubMed® and Cochrane® databases. Recommendations from learned societies in diabetology and obstetrics & gynaecology were consulted.

RESULTS

Gestational diabetes mellitus screening is classically recommended between weeks 24 and 28 of pregnancy, the period during which glucose tolerance deteriorates. However, the increasing prevalence of type 2 diabetes in women of childbearing age with risk factors requires earlier screening. Fasting blood glucose should be measured at the fi rst visit during early pregnancy for these patients. The diagnostic threshold is the same as for patients who are not pregnant, i.e. blood glucose > 1.26 g/l. However, the benefit of screening for gestational diabetes during early pregnancy for women with risk factors has not been supported by prospective studies. Therefore oral glucose tolerance testing during early pregnancy is not currently recommended for the detection of gestational diabetes. Screening for gestational diabetes, regardless of the recommended screening policy, must be performed between weeks 24 and 28 of pregnancy. There are no reasons to consider subsequent screening for gestational diabetes at a later stage.

Serum dipeptidyl peptidase-4 activity in insulin resistant patients with non-alcoholic fatty liver disease: a novel liver disease biomarker

Background

In a cross-sectional study we studied the fasting serum DPP-4 enzymatic activity (sDPP-4) and the insulin resistance index (HOMA2-IR) in gliptin naïve patients with type 2 diabetes and in non-alcoholic fatty liver disease (NAFLD) and in healthy controls (CNTRL).

Methods and Findings

sDPP-4 was measured by kinetic assay in 39 NAFLD (F/M:19/20, mean age: 47.42 yrs) and 82 type 2 diabetes (F/M:48/34, 62.8 yrs) patients and 26 (F/M:14/12, 35.3 yrs) controls. Definition of T2D group as patients with type 2 diabetes but without clinically obvious liver disease created non-overlapping study groups. Diagnosis of NAFLD was based on ultrasonography and the exclusion of other etiololgy. Patients in T2D and NAFLD groups were similarly obese. 75 g CH OGTT in 39 NAFLD patients: 24-NGT, 4-IGT or IFG (“prediabetes”), 11-type 2 diabetes. HOMA2-IR: CNTRL: 1.44; T2D-group: 2.62 (p = 0.046 vs CNTRL, parametric tests); NAFLD(NGTonly): 3.23 (p = 0.0013 vs CNTRL); NAFLD(IFG/IGT/type 2 diabetes): 3.82 (p<0.001 vs CNTRL, p = 0.049 vs 2TD group). sDPP-4 activity was higher in NAFLD both with NGT (mean:33.08U/L) and abnormal glucose metabolism (30.38U/L) than in CNTRL (25.89U/L, p<0.001 and p = 0.013) or in T2D groups (23.97U/L, p<0.001 and p = 0.004). Correlations in NAFLD among sDPP-4 and ALT: r = 0.4637,p = 0.0038 and γGT: r = 0.4991,p = 0.0017 and HOMA2-IR: r = 0.5295,p = 0.0026 and among HOMA2-IR and ALT: r = 0.4340,p = 0.0147 and γGT: r = 0.4128,p = 0.0210.

Conclusions

The fasting serum DPP-4 activity was not increased in T2D provided that patients with liver disease were intentionally excluded. The high serum DPP-4 activities in NAFLD were correlated with liver tests but not with the fasting plasma glucose or HbA1C supporting that the excess is of hepatic origin and it might contribute to the speedup of metabolic deterioration. The correlation among γGT, ALT and serum DPP-4 activity and also between serum DPP-4 activity and HOMA2-IR in NAFLD strongly suggests that serum DPP-4 activity should be considered as a novel liver disease biomarker.