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This study aimed to design a simple surrogate marker (i.e., predictor) of the minimal model glucose effectiveness (SG), namely calculated SG (CSG), from a short insulin-modified intravenous glucose tolerance test (IM-IVGTT), and then to apply it to study women with previous gestational diabetes mellitus (pGDM).
CSG was designed using the stepwise model selection approach on a population of subjects (
CSG was described as CSG=1.06×10−2+5.71×10−2×KG/Gpeak, KG being the mean slope (absolute value) of loge glucose in 10–25- and 25–50-minute intervals, and Gpeak being the maximum of the glucose curve. Good agreement between CSG and SG in the general population and in the pGDM group, both at baseline and follow-up (even in PROG and NONPROG subgroups), was shown by the Bland-Altman plots (<5% observations outside limits of agreement), and by the test for equivalence (equivalence margin not higher than one standard deviation). At baseline, the PROG subgroup showed significantly lower SG and CSG values compared to the NONPROG subgroup (
CSG is a valid SG predictor. In the pGDM group, glucose effectiveness appeared to be impaired in women progressing to T2DM.
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We investigated the pregnancy outcomes in women who were diagnosed with gestational diabetes mellitus (GDM) by the International Association of the Diabetes and Pregnancy Study Groups (IADPSG) criteria but not by the Carpenter-Coustan (CC) criteria.
A total of 8,735 Korean pregnant women were identified at two hospitals between 2014 and 2016. Among them, 2,038 women participated in the prospective cohort to investigate pregnancy outcomes. Diagnosis of GDM was made via two-step approach with 50-g glucose challenge test for screening followed by diagnostic 2-hour 75-g oral glucose tolerance test. Women were divided into three groups: non-GDM, GDM diagnosed exclusively by the IADPSG criteria, and GDM diagnosed by the CC criteria.
The incidence of GDM was 2.1% according to the CC criteria, and 4.1% by the IADPSG criteria. Women diagnosed with GDM by the IADPSG criteria had a higher body mass index (22.0±3.1 kg/m2 vs. 21.0±2.8 kg/m2,
The IADPSG criteria increased the incidence of GDM by nearly three-fold, and women diagnosed with GDM by the IADPSG criteria had an increased risk of adverse pregnancy outcomes in Korea.
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Women with one abnormal value (OAV) in a 100 g oral glucose tolerance test (OGTT) during pregnancy are reported to have an increased risk of adverse pregnancy outcomes. However, there is limited data about whether women with OAV will progress to gestational diabetes mellitus (GDM) when the OGTT is repeated.
To identify clinical and metabolic predictors for GDM in women with OAV, we conducted a retrospective study and identified women with OAV in the OGTT done at 24 to 30 weeks gestational age (GA) and repeated the second OGTT between 32 and 34 weeks of GA.
Among 137 women with OAV in the initial OGTT, 58 (42.3%) had normal, 40 (29.2%) had OAV and 39 (28.5%) had GDM in the second OGTT. Maternal age, prepregnancy body mass index, weight gain from prepregnancy to the second OGTT, GA at the time of the OGTT, and parity were similar among normal, OAV, and GDM groups. Plasma glucose levels in screening tests were different (151.8±15.7, 155.8±14.6, 162.5±20.3 mg/dL,
We demonstrated that women with OAV in the initial OGTT significantly progressed to GDM in the second OGTT. Clinical parameters predicting progression to GDM were not found. Repeating the OGTT in women with OAV in the initial test may be helpful to detect GDM progression.
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We aimed to identify the postpartum metabolic factors that were associated with the development of diabetes in women with a history of gestational diabetes mellitus (GDM). In addition, we examined the role of the oral glucose tolerance test (OGTT) in the prediction of future diabetes.
We conducted a prospective study of 179 subjects who previously had GDM but did not have diabetes at 2 months postpartum. The initial postpartum examination including a 75-g OGTT and the frequently sampled intravenous glucose tolerance test (FSIVGTT) was performed 12 months after delivery, and annual follow-up visits were made thereafter.
The insulinogenic index (IGI30) obtained from the OGTT was significantly correlated with the acute insulin response to glucose (AIRg) obtained from the FSIVGTT. The disposition indices obtained from the OGTT and FSIVGTT were also significantly correlated. Women who progressed to diabetes had a lower insulin secretory capacity including IGI30, AIRg, and disposition indices obtained from the FSIVGTT and OGTT compared with those who did not. However, the insulin sensitivity indices obtained from the OGTT and FSIVGTT did not differ between the two groups. Multivariate logistic regression analysis showed that the 2-hour glucose and disposition index obtained from the FSIVGTT were significant postpartum metabolic risk factors for the development of diabetes.
We identified a crucial role of β-cell dysfunction in the development of diabetes in Korean women with previous GDM. The 2-hour glucose result from the OGTT is an independent predictor of future diabetes. Therefore, the OGTT is crucial for better prediction of future diabetes in Korean women with previous GDM.
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Little is known about the natural course of normal fasting glucose (NFG) in Asians and the risk factors for future diabetes.
A total of 370 Japanese Americans (163 men, 207 women) with NFG levels and no history of diabetes, aged 34 to 75 years, were enrolled. Oral glucose tolerance tests were performed at baseline, 2.5, 5, and 10 years after enrollment.
During 10 years of follow-up, 16.1% of participants met criteria for diabetes diagnosis, and 39.6% of subjects still had NFG levels at the time of diabetes diagnosis. During 5 years of follow-up, age (odds ratio [OR], 1.05; 95% confidence interval [CI], 1.01 to 1.10;
A substantial number of subjects with NFG at baseline still remained in the NFG range at the time of diabetes diagnosis. A family history of diabetes and fasting insulin and glucose levels were associated with diabetes diagnosis during 10 years of follow-up; however, fasting glucose level was not associated with diabetes risk within the relatively short-term follow-up period of 5 years in subjects with NFG.
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The purpose of this study was to examine the effect of regular exercise training on insulin sensitivity in adults with type 2 diabetes mellitus (T2DM) using the pooled data available from randomised controlled trials. In addition, we sought to determine whether short-term periods of physical inactivity diminish the exercise-induced improvement in insulin sensitivity. Eligible trials included exercise interventions that involved ≥3 exercise sessions, and reported a dynamic measurement of insulin sensitivity. There was a significant pooled effect size (ES) for the effect of exercise on insulin sensitivity (ES, –0.588; 95% confidence interval [CI], –0.816 to –0.359;
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Antidiabetic Effects of Physical Activity: How It Helps to Control Type 2 Diabetes
The oral minimal model is a simple, useful tool for the assessment of β-cell function and insulin sensitivity across the spectrum of glucose tolerance, including normal glucose tolerance (NGT), prediabetes, and type 2 diabetes mellitus (T2DM) in humans.
Plasma glucose, insulin, and C-peptide levels were measured during a 180-minute, 75-g oral glucose tolerance test in 24 Korean subjects with NGT (
The insulin sensitivity index was lower in the T2DM group than the NGT group. The basal index of β-cell responsivity, basal hepatic insulin extraction ratio, and post-glucose challenge hepatic insulin extraction ratio were not different between the NGT and T2DM groups. The dynamic, static, and total β-cell responsivity indexes were significantly lower in the T2DM group than the NGT group. The dynamic, static, and total disposition indexes were also significantly lower in the T2DM group than the NGT group.
The oral minimal model can be reproducibly applied to evaluate β-cell function and insulin sensitivity in Koreans.
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We evaluated the diagnostic rate of diabetes using fasting plasma glucose (FPG), 2-hour plasma glucose (2h PG) after 75 g oral glucose tolerance test (OGTT), and glycosylated hemoglobin (HbA1c) levels, and we elucidated the pathophysiologic characteristics and risk factors that give rise to diabetes in patients with prediabetes.
The data of 236 patients who had the OGTT at Konkuk University Hospital were analyzed. Fasting, 30, and 120 minutes blood glucose levels and insulin levels were measured. The diagnostic rate of diabetes was assessed using FPG, 2h PG, and HbA1c levels. The clinical data and insulin resistance and secretion evaluations were compared using indexes according to the fasting glucose level.
Among 236 subjects, 97 (41.1%) were diabetics and 102 (43.2%) were prediabetics. The rate of diabetes diagnosis by one of the individual criteria was 56.7%, 53.6%, and 84.5% for FPG, HbA1c, and 2h PG, respectively. When two criteria were used to diagnose diabetes, 72.2% of the diabetic patients were identified by FPG and HbA1c, while 100% were identified by FPG and 2h PG, and 91.7% were identified by 2h PG and HbA1c. The HbA1c cut-off value for 2h PG ≥200 mg/dL was 6.1%, and the FPG cut-off value was 115 mg/dL. In impaired fasting glucose subjects, the HbA1c level, Matsuda index, and insulinogenic index were associated with risk of occurrence of overt diabetes (
This study suggests that performing additional OGTT for patients with FPG ≥110 mg/dL or HbA1c ≥6.1% is helpful to reclassify their glucose tolerance status and evaluate their potential for progressing to overt diabetes.
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We investigated the therapeutic effects of resistance training on Zucker rats before and after the onset of diabetes to understand the importance of the timing of exercise intervention. We assessed whether 8 weeks of resistance training ameliorated impaired glucose tolerance and altered muscle fiber type composition in Zucker rats.
Five-week-old male Zucker rats were divided into Zucker lean control (ZLC-Con), non-exercised Zucker diabetic fatty (ZDF-Con), and exercised Zucker diabetic fatty (ZDF-Ex) groups. The ZDF-Ex rats climbed a ladder three times a week for 8 weeks. Intraperitoneal glucose tolerance tests (IPGTT) were performed on the 1st and 8th weeks of training, and grip strength was measured during the last week. We also measured glucose transporter 4 (GLUT4) expression by Western blot and immunofluorescence. Moreover, immunohistochemistry was performed to assess muscle fiber type composition.
Fasting glucose levels and area under the curve responses to IPGTTs gradually increased as diabetes progressed in the ZDF-Con rats but decreased in the ZDF-Ex rats. Grip strength decreased in the ZDF-Con rats. However, resistance training did not improve grip strength in the ZDF-Ex rats. GLUT4 expression in the ZLC-Con and the ZDF-Con rats did not differ, but it increased in the ZDF-Ex rats. The proportions of myosin heavy chain I and II were lower and higher, respectively, in the ZDF-Con rats compared to the ZLC-Con rats. Muscle fiber type composition did not change in the ZDF-Ex rats.
Our results suggest that regular resistance training initiated at the onset of diabetes can improve glucose tolerance and GLUT4 expression without changing muscle morphology in Zucker rats.
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This study aimed to evaluate the effect of sitagliptin, an oral dipeptidyl peptidase-4 inhibitor, on insulin secretion and glucagon suppression in Korean subjects with type 2 diabetes mellitus.
Twenty-four subjects underwent a 75-g oral glucose tolerance test (OGTT) before and after 6 months of sitagliptin treatment. Sitagliptin, insulin, and sulfonylurea were withdrawn for 3 days before OGTT to eliminate any acute effects on β-cell insulin or α-cell glucagon secretion. Venous samples were drawn five times during each OGTT to measure plasma glucose, insulin, and glucagon. Indices on insulin secretion and resistance were calculated.
Early phase insulin secretion, measured by the insulinogenic index significantly increased after 6 months of sitagliptin treatment, especially in the higher baseline body mass index group and higher baseline glycosylated hemoglobin (HbA1c) group. There were no significant differences in the insulin resistance indices before and after sitagliptin treatment. Although no significant differences were observed in the absolute levels of glucagon and the glucagon-to-insulin ratio, there was a significant reduction in the percentile change of glucagon-to-insulin ratio at 30- and 120-minute during the OGTT.
Although the HbA1c level did not decrease significantly after 6 months of sitagliptin treatment, an increase in insulin secretion and reduction in early phase postprandial plasma glucagon-to-insulin ratio excursion was confirmed in Korean subjects with type 2 diabetes.
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This study aimed to compare the patterns of insulin secretion and resistance between Korean subjects in the 1990s and 2000s.
Insulin secretion and resistance indices were calculated from subjects who underwent 75-g oral glucose tolerance tests in the year 1997 to 1999 and 2007 to 2011 at the Seoul St. Mary's Hospital, Korea.
A total of 578 subjects from the 1990s (mean age, 48.5 years) and 504 subjects from the 2000s (mean age, 50.2 years) were enrolled. Compared with the subjects from the 1990s, those from the 2000s exhibited increased insulin resistance (increased homeostatic model assessment for insulin resistance), and reduced insulin sensitivity (reduced Matsuda index and quantitative insulin sensitivity check index), regardless of their glucose tolerance status. However, insulinogenic index did not reveal significant differences between the 2 decades in subjects with or without diabetes. A distinct relationship was confirmed between Matsuda index and total area under the curve (insulin/glucose) in each glucose tolerance group. The mean product of the Matsuda index and the total area under the curve (insulin/glucose) as well as the oral disposition index, was lower in subjects with normal glucose tolerance from the 2000s than in those from the 1990s.
After rapid economic growth and changes in lifestyle patterns, insulin resistance has worsened across the glucose tolerance status; however, the insulin secretory function remained unchanged, which resulted in an increase in the susceptibility to the development of type 2 diabetes mellitus among Korean subjects without diabetes. We could not rule out the potential selection bias and therefore, further studies in general Korean population are needed.
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Subjects with normal glucose tolerance (NGT) who have a high 1-hour postload plasma glucose level (≥155 mg/dL; NGT 1 hour-high) have been shown to be at higher risk for type 2 diabetes than subjects with NGT 1 hour-low postload plasma glucose level (<155 mg/dL). We compared β-cell function in subjects with NGT 1 hour-high, NGT 1 hour-low, and impaired glucose tolerance (IGT).
We classified subjects into NGT 1 hour-low (
Insulin sensitivity was comparable between the subjects with NGT 1 hour-high and NGT 1 hour-low. The β-cell function with/without adjusting insulin sensitivity was significantly different among the three groups. The IGI (pmol/mmol) was 116.8±107.3 vs. 64.8±47.8 vs. 65.8±80.6 (
Among Korean subjects with NGT, those who have a higher 1-hour postload glucose level have a compromised insulin-sensitivity adjusted β-cell function to a similar degree as IGT subjects.
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As with the dramatic increases in childhood obesity over the past decades, the incidence of type 2 diabetes has increased among children and adolescents in the United States. Insulin resistance is a common feature of childhood obesity and increases the risk of type 2 diabetes, metabolic syndrome, and atherogenic lipoprotein profile in obese youth. Although cross-sectional studies report beneficial effects of physical activity or cardiorespiratory fitness on insulin sensitivity, the role of regular exercise alone (e.g., no calorie restriction) as a strategy to reduce the risk of type 2 diabetes is unclear in obese children and adolescents. In this mini review, we examined the independent effects of various exercise on glucose tolerance and insulin sensitivity in obese youth.
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