Original Article Gynecol Obstet Invest 2014;78:53–58 DOI: 10.1159/000362230
Received: September 5, 2013 Accepted after revision: March 16, 2014 Published online: May 31, 2014
Inflammation and Glycemic Tolerance Status in Pregnancy: The Role of Maternal Adiposity Şebnem Özyer Yaprak Engin-Üstün Özlem Uzunlar Ceren Katar Nuri Danışman Zekai Tahir Burak Women’s Health Education and Research Hospital, Ankara, Turkey
Key Words Inflammation · Gestational diabetes mellitus · Obesity · C-reactive protein · Fibrinogen
Abstract Background/Aims: Although the association between inflammation and insulin resistance is well known, the data related to the role of inflammation in gestational diabetes mellitus (GDM) are conflicting. The aim of this study was to investigate the association of several inflammatory mediators with the glycemic status in pregnancy. Methods: Leukocyte count, ferritin, C-reactive protein (CRP), fibrinogen and interleukin-6 levels were measured in 70 patients with normal glucose tolerance, in 57 patients with impaired glucose tolerance and in 35 patients with GDM as determined based on 50-gram oral glucose tolerance test (OGTT) and 100-gram OGTT results. Results: A significant difference among the groups was seen only with regard to CRP and fibrinogen levels; however, no significant differences were observed after adjustment for body mass index (BMI). CRP was found to be strongly associated with current BMI in all three groups. Conclusion: Maternal serum levels of inflammatory mediators are not related to GDM at the time of the glucose challenge test in the late second or early third trimester. The significant difference in the levels of CRP in different strata of glycemic
© 2014 S. Karger AG, Basel 0378–7346/14/0781–0053$39.50/0 E-Mail [email protected] www.karger.com/goi
tolerance was not observed after adjustment for BMI. Adiposity may have a central role in GDM, causing an inflammatory response. © 2014 S. Karger AG, Basel
Introduction
Many studies suggest that inflammation may be an underlying pathophysiologic mechanism contributing to the development of many adverse clinical outcomes, including type 2 diabetes mellitus (T2DM), metabolic syndrome, obesity and atherosclerotic vascular disease [1]. Proinflammatory cytokines released from adipose tissue [interleukin (IL)-6, tumor necrosis factor (TNF)-α and adiponectin], as well as other acute-phase inflammatory mediators, such as leukocyte count, plasma activator inhibitor-1, fibrinogen and C-reactive protein (CRP), can contribute to the future development of T2DM and cardiovascular disease [2]. Gestational diabetes mellitus (GDM) is a common metabolic complication of pregnancy that shares many features of T2DM, including glucose intolerance and insulin resistance [3]. A potential pathophysiologic relationship between GDM and T2DM is further supported by the significantly elevated lifetime risk of T2DM in women Dr. Şebnem Özyer Birlik mah 406 sok No 15/9, Çankaya TR–Ankara (Turkey) E-Mail sebnemsenozyer @ yahoo.com
with a history of previous GDM [4]. In a recent study investigating the incidence of glucose intolerance during the first year postpartum in women with GDM, it was demonstrated that women with GDM, mainly those who remained obese, develop a significantly increased risk of glucose intolerance [5]. Furthermore, 30–70% of GDM patients may develop T2DM at a later age [6], making GDM a clinical condition which must be handled seriously. The association between inflammation and insulin resistance is well known and supported by several previous clinical reports [7–9]. Studies have shown that there is a positive statistical correlation between insulin sensitivity and inflammatory markers, such as CRP, IL-6 and TNF-α [9, 10]. Similarly, there are studies in the literature investigating the possible role of systemic inflammation in GDM; however, their results are conflicting. Inflammation has been linked to excessive adiposity, and Wolf et al. [11], Bo et al. [12] and Retnakaran et al. [1] found that an increase in CRP levels during pregnancy was strongly associated with maternal obesity. A recent study by Nicholson et al. [13] investigating the predictive value of firsttrimester adiponectin and TNF-α concentrations for maternal glucose tolerance showed that TNF-α levels were not associated with the glucose challenge test (GCT) and first-trimester adiponectin levels are not predictive of the GCT response but may be a marker for the effect of maternal body mass index (BMI) on the glucose response to the GCT. In contrast, Qiu et al. [14] reported that the association between elevated CRP levels and GDM risk was independent of maternal prepregnancy adiposity. Furthermore, D’Anna et al. [15], in a cohort of women who were recruited at 14–16 weeks of gestation and followed until delivery, found that CRP had no predictive value for GDM, and no positive correlation was found between BMI and this inflammatory marker. In this regard, we aimed to investigate the association of several inflammatory mediators, namely leukocyte count, ferritin, CRP, fibrinogen and IL-6, with glycemic status in pregnancy. We further evaluated the association of these inflammatory mediators with some other clinical and biochemical parameters related with the risk of GDM.
Patients and Methods One hundred and sixty-two pregnant women were included in this prospective case-control study which was conducted between April and June 2012. All patients were screened using a standard 50-gram oral glucose tolerance test (OGTT) at 24–28 weeks of gestation. A threshold value of 140 mg/dl was accepted to define the women with normal glucose tolerance (NGT; n = 70). Those wom-
54
Gynecol Obstet Invest 2014;78:53–58 DOI: 10.1159/000362230
en who failed this screening test (postload glucose concentrations ≥140 mg/dl) were then followed up with a diagnostic, fasting, 100gram, 3-hour OGTT. GDM (n = 35) was diagnosed if 2 or more of the plasma glucose concentrations were abnormal, i.e. fasting ≥95 mg/dl, 1-hour ≥180 mg/dl, 2-hour ≥155 mg/dl or 3-hour ≥140 mg/ dl according to the Carpenter and Coustan criteria as recommended by the American Diabetes Association [16]. Women with only 1 abnormal value were defined as having impaired glucose tolerance (IGT; n = 57). All the patients diagnosed as having GDM or IGT during the study period were included in the study. Two consecutive NGT patients for each GDM patient were taken as controls. Information including age, medical and obstetric history, infections, drug treatments, smoking, height and weight was collected. Exclusion criteria included the following: (1) preexisting medical conditions that may increase acute-phase markers including diabetes mellitus, collagen vascular diseases, inflammatory diseases and chronic hypertension; (2) use of corticosteroids; (3) current infection; (4) smoking, and (5) multiple gestation. Fasting white blood cell, ferritin, CRP, fibrinogen and IL-6 levels were determined either after the 50-gram OGTT in NGT women or on the day of the 100-gram OGTT in women with IGT or GDM. Serum glucose levels were measured by a Roche Modular P autoanalyzer using standard enzymatic methods (Cobas, Roche Diagnostics, Mannheim, Germany). Leukocyte count was determined by a Mindray auto-hematology analyzer (Mindray Medical International Limited, China). Serum ferritin and IL-6 were measured using a solid-phase, enzyme-labeled, chemiluminescent sequential immunometric assay (Siemens Healthcare Diagnostic Products, UK). Fibrinogen was measured using Dade Thrombin Reagent by the Clauss method (Siemens Healthcare Diagnostic Products). Serum high-sensitivity CRP concentrations were determined by a high-sensitive particle-enhanced immunoturbidimetric assay (Roche Diagnostics, USA). All statistical analyses were performed with SPSS for Windows 16.0 (SPSS Inc., Chicago, Ill., USA). Means ± standard deviations and medians and interquartile ranges are given for normally and nonnormally distributed continuous variables, respectively. Frequencies and percentages are given for categorical variables. χ2 test, one-way analysis of variance (ANOVA) and the Kruskal-Wallis test were used to assess the differences between groups. The Tukey honestly significant difference test and Dunn’s test were used for post hoc analysis for ANOVA and the Kruskal-Wallis test, respectively. Analysis of covariance was used to test differences between groups after adjustment for the covariate BMI. In this analysis, the natural logarithmic transformations of CRP, ferritin and IL-6 were used.
Results
Characteristics of the sample of 162 women are shown in table 1. There were no differences in terms of age and gestational week among the groups. There was a significant difference in current BMI among the groups, with lower values in the NGT group when compared with the IGT and GDM groups (25.3 ± 3.8, 29.2 ± 5.0 and 30.4 ± 4.3, respectively; p < 0.001). Glycemic parameters of fasting, 1-hour, 2-hour and 3-hour glucose concentrations Özyer/Engin-Üstün/Uzunlar/Katar/ Danışman
Table 1. Demographic and metabolic characteristics and inflammatory markers of pregnant patients with different glycemic tolerance
status Characteristic
NGT (n = 70)
IGT (n = 57)
GDM (n = 35)
Age, years Gestational week Current BMI Parity, % Nulliparous Multiparous 50-Gram OGTT, mg/dl Fasting glucose, mg/dl Post-OGTT glucose, mg/dl 1h 2h 3h WBC count, ×103/μl Ferritin, ng/ml CRP, mg/l Fibrinogen, mg/dl IL-6, pg/ml
29.2 ± 2.4 26.3 ± 0.9 25.3 ± 3.8*
30.5 ± 5.1 26 ± 0.9 29.2 ± 5.0
30.7 ± 3.4 25.9 ± 0.7 30.4 ± 4.3
53.7 46.3 105.5 ± 19.5 82.8 ± 9.9
33.3 66.7 161.9 ± 16.6 80.0 ± 8.5
20.0 80.0 177.4 ± 25.6 98.1 ± 29.1*
10,639 ± 2,019 14.25 (7.35 – 18.88) 3.84 (1.86 – 7.01)* 394.9 ± 92.6+ 2.0 (2.0 – 2.00)
178.3 ± 22.9 126.6 ± 27.5 93.5 ± 33.9 11,130 ± 2,508 16.65 (7.53 – 26.00) 5.19 (3.05 – 11.79) 404.9 ± 77.7 2.0 (2.0 – 3.75)
pa
p 0.098 0.053
Received: September 5, 2013 Accepted after revision: March 16, 2014 Published online: May 31, 2014
Inflammation and Glycemic Tolerance Status in Pregnancy: The Role of Maternal Adiposity Şebnem Özyer Yaprak Engin-Üstün Özlem Uzunlar Ceren Katar Nuri Danışman Zekai Tahir Burak Women’s Health Education and Research Hospital, Ankara, Turkey
Key Words Inflammation · Gestational diabetes mellitus · Obesity · C-reactive protein · Fibrinogen
Abstract Background/Aims: Although the association between inflammation and insulin resistance is well known, the data related to the role of inflammation in gestational diabetes mellitus (GDM) are conflicting. The aim of this study was to investigate the association of several inflammatory mediators with the glycemic status in pregnancy. Methods: Leukocyte count, ferritin, C-reactive protein (CRP), fibrinogen and interleukin-6 levels were measured in 70 patients with normal glucose tolerance, in 57 patients with impaired glucose tolerance and in 35 patients with GDM as determined based on 50-gram oral glucose tolerance test (OGTT) and 100-gram OGTT results. Results: A significant difference among the groups was seen only with regard to CRP and fibrinogen levels; however, no significant differences were observed after adjustment for body mass index (BMI). CRP was found to be strongly associated with current BMI in all three groups. Conclusion: Maternal serum levels of inflammatory mediators are not related to GDM at the time of the glucose challenge test in the late second or early third trimester. The significant difference in the levels of CRP in different strata of glycemic
© 2014 S. Karger AG, Basel 0378–7346/14/0781–0053$39.50/0 E-Mail [email protected] www.karger.com/goi
tolerance was not observed after adjustment for BMI. Adiposity may have a central role in GDM, causing an inflammatory response. © 2014 S. Karger AG, Basel
Introduction
Many studies suggest that inflammation may be an underlying pathophysiologic mechanism contributing to the development of many adverse clinical outcomes, including type 2 diabetes mellitus (T2DM), metabolic syndrome, obesity and atherosclerotic vascular disease [1]. Proinflammatory cytokines released from adipose tissue [interleukin (IL)-6, tumor necrosis factor (TNF)-α and adiponectin], as well as other acute-phase inflammatory mediators, such as leukocyte count, plasma activator inhibitor-1, fibrinogen and C-reactive protein (CRP), can contribute to the future development of T2DM and cardiovascular disease [2]. Gestational diabetes mellitus (GDM) is a common metabolic complication of pregnancy that shares many features of T2DM, including glucose intolerance and insulin resistance [3]. A potential pathophysiologic relationship between GDM and T2DM is further supported by the significantly elevated lifetime risk of T2DM in women Dr. Şebnem Özyer Birlik mah 406 sok No 15/9, Çankaya TR–Ankara (Turkey) E-Mail sebnemsenozyer @ yahoo.com
with a history of previous GDM [4]. In a recent study investigating the incidence of glucose intolerance during the first year postpartum in women with GDM, it was demonstrated that women with GDM, mainly those who remained obese, develop a significantly increased risk of glucose intolerance [5]. Furthermore, 30–70% of GDM patients may develop T2DM at a later age [6], making GDM a clinical condition which must be handled seriously. The association between inflammation and insulin resistance is well known and supported by several previous clinical reports [7–9]. Studies have shown that there is a positive statistical correlation between insulin sensitivity and inflammatory markers, such as CRP, IL-6 and TNF-α [9, 10]. Similarly, there are studies in the literature investigating the possible role of systemic inflammation in GDM; however, their results are conflicting. Inflammation has been linked to excessive adiposity, and Wolf et al. [11], Bo et al. [12] and Retnakaran et al. [1] found that an increase in CRP levels during pregnancy was strongly associated with maternal obesity. A recent study by Nicholson et al. [13] investigating the predictive value of firsttrimester adiponectin and TNF-α concentrations for maternal glucose tolerance showed that TNF-α levels were not associated with the glucose challenge test (GCT) and first-trimester adiponectin levels are not predictive of the GCT response but may be a marker for the effect of maternal body mass index (BMI) on the glucose response to the GCT. In contrast, Qiu et al. [14] reported that the association between elevated CRP levels and GDM risk was independent of maternal prepregnancy adiposity. Furthermore, D’Anna et al. [15], in a cohort of women who were recruited at 14–16 weeks of gestation and followed until delivery, found that CRP had no predictive value for GDM, and no positive correlation was found between BMI and this inflammatory marker. In this regard, we aimed to investigate the association of several inflammatory mediators, namely leukocyte count, ferritin, CRP, fibrinogen and IL-6, with glycemic status in pregnancy. We further evaluated the association of these inflammatory mediators with some other clinical and biochemical parameters related with the risk of GDM.
Patients and Methods One hundred and sixty-two pregnant women were included in this prospective case-control study which was conducted between April and June 2012. All patients were screened using a standard 50-gram oral glucose tolerance test (OGTT) at 24–28 weeks of gestation. A threshold value of 140 mg/dl was accepted to define the women with normal glucose tolerance (NGT; n = 70). Those wom-
54
Gynecol Obstet Invest 2014;78:53–58 DOI: 10.1159/000362230
en who failed this screening test (postload glucose concentrations ≥140 mg/dl) were then followed up with a diagnostic, fasting, 100gram, 3-hour OGTT. GDM (n = 35) was diagnosed if 2 or more of the plasma glucose concentrations were abnormal, i.e. fasting ≥95 mg/dl, 1-hour ≥180 mg/dl, 2-hour ≥155 mg/dl or 3-hour ≥140 mg/ dl according to the Carpenter and Coustan criteria as recommended by the American Diabetes Association [16]. Women with only 1 abnormal value were defined as having impaired glucose tolerance (IGT; n = 57). All the patients diagnosed as having GDM or IGT during the study period were included in the study. Two consecutive NGT patients for each GDM patient were taken as controls. Information including age, medical and obstetric history, infections, drug treatments, smoking, height and weight was collected. Exclusion criteria included the following: (1) preexisting medical conditions that may increase acute-phase markers including diabetes mellitus, collagen vascular diseases, inflammatory diseases and chronic hypertension; (2) use of corticosteroids; (3) current infection; (4) smoking, and (5) multiple gestation. Fasting white blood cell, ferritin, CRP, fibrinogen and IL-6 levels were determined either after the 50-gram OGTT in NGT women or on the day of the 100-gram OGTT in women with IGT or GDM. Serum glucose levels were measured by a Roche Modular P autoanalyzer using standard enzymatic methods (Cobas, Roche Diagnostics, Mannheim, Germany). Leukocyte count was determined by a Mindray auto-hematology analyzer (Mindray Medical International Limited, China). Serum ferritin and IL-6 were measured using a solid-phase, enzyme-labeled, chemiluminescent sequential immunometric assay (Siemens Healthcare Diagnostic Products, UK). Fibrinogen was measured using Dade Thrombin Reagent by the Clauss method (Siemens Healthcare Diagnostic Products). Serum high-sensitivity CRP concentrations were determined by a high-sensitive particle-enhanced immunoturbidimetric assay (Roche Diagnostics, USA). All statistical analyses were performed with SPSS for Windows 16.0 (SPSS Inc., Chicago, Ill., USA). Means ± standard deviations and medians and interquartile ranges are given for normally and nonnormally distributed continuous variables, respectively. Frequencies and percentages are given for categorical variables. χ2 test, one-way analysis of variance (ANOVA) and the Kruskal-Wallis test were used to assess the differences between groups. The Tukey honestly significant difference test and Dunn’s test were used for post hoc analysis for ANOVA and the Kruskal-Wallis test, respectively. Analysis of covariance was used to test differences between groups after adjustment for the covariate BMI. In this analysis, the natural logarithmic transformations of CRP, ferritin and IL-6 were used.
Results
Characteristics of the sample of 162 women are shown in table 1. There were no differences in terms of age and gestational week among the groups. There was a significant difference in current BMI among the groups, with lower values in the NGT group when compared with the IGT and GDM groups (25.3 ± 3.8, 29.2 ± 5.0 and 30.4 ± 4.3, respectively; p < 0.001). Glycemic parameters of fasting, 1-hour, 2-hour and 3-hour glucose concentrations Özyer/Engin-Üstün/Uzunlar/Katar/ Danışman
Table 1. Demographic and metabolic characteristics and inflammatory markers of pregnant patients with different glycemic tolerance
status Characteristic
NGT (n = 70)
IGT (n = 57)
GDM (n = 35)
Age, years Gestational week Current BMI Parity, % Nulliparous Multiparous 50-Gram OGTT, mg/dl Fasting glucose, mg/dl Post-OGTT glucose, mg/dl 1h 2h 3h WBC count, ×103/μl Ferritin, ng/ml CRP, mg/l Fibrinogen, mg/dl IL-6, pg/ml
29.2 ± 2.4 26.3 ± 0.9 25.3 ± 3.8*
30.5 ± 5.1 26 ± 0.9 29.2 ± 5.0
30.7 ± 3.4 25.9 ± 0.7 30.4 ± 4.3
53.7 46.3 105.5 ± 19.5 82.8 ± 9.9
33.3 66.7 161.9 ± 16.6 80.0 ± 8.5
20.0 80.0 177.4 ± 25.6 98.1 ± 29.1*
10,639 ± 2,019 14.25 (7.35 – 18.88) 3.84 (1.86 – 7.01)* 394.9 ± 92.6+ 2.0 (2.0 – 2.00)
178.3 ± 22.9 126.6 ± 27.5 93.5 ± 33.9 11,130 ± 2,508 16.65 (7.53 – 26.00) 5.19 (3.05 – 11.79) 404.9 ± 77.7 2.0 (2.0 – 3.75)
pa
p 0.098 0.053
