Physical fitness, insulin secretion, and glucose tolerance in healthy males and mild type-2 diabetes
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Glucose tolerance test
Abstract Objective We aimed to assess the order of severity of the defects of 3 direct determinants of glucose regulation—beta-cell function, insulin clearance, and insulin sensitivity—in patients with cystic fibrosis (CF), categorized according their glucose tolerance status, including early elevation of mid-level oral glucose tolerance test (OGTT) glucose values (>140 and <200 mg/dL), referred to as AGT140. Methods A total of 232 CF patients aged 10 to 25 years underwent OGTT. Beta-cell function and insulin clearance were estimated by OGTT mathematical modeling and OGTT-derived biomarkers of insulin secretion and sensitivity were calculated. The association between glucometabolic variables and 5 glucose tolerance stages (normal glucose tolerance [NGT], AGT140, indeterminate glucose tolerance [INDET], impaired glucose tolerance [IGT], cystic fibrosis–related diabetes CFRD]) was assessed with a general linear model. Results Beta-cell function and insulin sensitivity progressively worsened across glucose tolerance stages (P < 0.001), with AGT140 patients significantly differing from NGT (all P < 0.01). AGT140 and INDET showed a degree of beta-cell dysfunction similar to IGT and CFRD, respectively (all P < 0.01). Insulin clearance was not significantly associated with glucose tolerance stages (P = 0.162). Each stage of glucose tolerance was uniquely identified by a specific combination of defects of the direct determinants of glucose regulation. Conclusions In CF patients, each of the 5 glucose tolerance stages shows a unique pattern of defects of the direct determinants of glucose regulation, with AGT140 patients significantly differing from NGT and being similar to IGT. These findings suggest that AGT140 should be recognized as a distinct glucose tolerance stage and that reconsideration of the grade of glucometabolic deterioration across glucose tolerance stages in CF is warranted.
Glucose tolerance test
Insulin response
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OBJECTIVE To evaluate the significance of transient impaired glucose tolerance (IGT) in terms of the risk of progression to NIDDM and the serum insulin response during oral glucose tolerance test (OGTT) in a prospective study on the natural history of IGT in South African Indians. RESEARCH DESIGN AND METHODS This is a report on 87 subjects who formed part of a 4-year prospective study in 128 subjects classified with IGT at baseline (year 0) using World Health Organization criteria for glucose tolerance. Subjects were reexamined at years 1 and 4. At year 1, based on OGTT results, the subjects were divided into three groups: transient IGT (normal glucose tolerance [trIGT], n = 40), persistent IGT (pIGT, n = 47), and diabetes (n = 41). Analysis was performed on the 87 subjects who were classified as IGT at year 0, but who had not progressed to NIDDM by year 1 of the study At baseline (year 0), a modified OGTT was performed; between years 1 and 4, the OGTT included timed midtest samples for plasma glucose and serum insulin. Analysis of predictive factors for progression to diabetes or reversion to normal glucose tolerance was undertaken using year 0 as baseline. RESULTS By year 4, 72 subjects (82.8%) completed the study Of the 32 subjects in the trIGT group, none (0%) had progressed to NIDDM, 11 (34.4%) had reverted to IGT (N-IGT), and 21 (65.6%) had persisted with normal glucose tolerance (N-N); of the 40 subjects in the pIGT group, 16 (40%) had progressed to NIDDM (IGT-D), 17 (42.5%) had persisted with IGT (IGT-IGT), and 7 (17.5%) had reverted to normal glucose tolerance (IGT-N). Significant predictive factors for reversion to normal glucose tolerance included absence of obesity (P = 0.0131, odds ratio [OR] 4.2, 95% CI 1.4–13.1) and 2-h plasma glucose level (P = 0.027, OR 2.4, 95% CI 1.11–5.13) at baseline (year 0). Intergroup (cross-sectional) analysis showed that the serum insulin response was higher in the pIGT than in the trIGT subgroup (fasting serum insulin: IGT-N vs. N-IGT and N-N, 16.9 ± 1.9 vs. 6.8 ± 2.1 and 6.1 ± 2.4 μU/ml, respectively, P < 0.001; 2-h postload serum insulin: IGT-IGT vs. N-IGT, 116.8 ± 2.2 vs. 60.3 ± 1.7 μU/ml, P < 0.05). By contrast, the insulinogenic index was higher in the trIGT subgroups both at year 1 (90-min: N-N vs. IGT-D, 48.9 ± 3.9 vs. 14.1 ± 2.5; P < 0.05) and at year 4 (N-N vs. remaining four subgroups, P < 0.01 at 60 min and 90 min). Intragroup (prospective) comparisons showed that in the N-IGT subgroup, the mean 2-h insulinogenic index was lower at year 4 than at year 1 (19.9 ± 1.7 vs. 66.0 ± 2.7; P < 0.05). CONCLUSIONS In this 4-year prospective study in South African Indians, transient IGT carries no risk of progression to NIDDM. The significant predictive factors for reversion to normal glucose tolerance include lower baseline obesity prevalence and 2-h postload plasma glucose level. Moreover, in this group, β-cell secretory function appeared to deteriorate with worsening of glucose tolerance.
Glucose tolerance test
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We have estimated the prevalence of diabetes and impaired glucose tolerance from the Busselton 1981 Population Survey using the 1980 World Health Organization (WHO) criteria. Standardized to the Australian non-Aboriginal population aged 25 years and over, the prevalence rates in this white community were 2.5% for known diabetes; 0.9% for newly discovered diabetes; 2.9% for impaired glucose tolerance; and 6.3% for all categories of abnormal glucose tolerance. There appears to have been a real increase in the frequency of diabetes since 1966. Using fasting serum C-peptide values and clinical criteria, 14% of all diabetic subjects were insulin-dependent. The male:female ratio for all categories of abnormal glucose tolerance was 1.4:1. Data from the United States indicate spectacularly higher rates for diabetes and impaired glucose tolerance in the white population. A national study of the prevalence of diabetes and impaired glucose tolerance in Australia is recommended. For epidemiological purposes, a single blood glucose value two hours after a 75 g oral glucose tolerance test is sufficient to categorize glucose tolerance as defined by WHO.
Glucose tolerance test
Impaired fasting glucose
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Summary. Of 218 pregnant women with abnormal glucose tolerance by the criteria of the World Health Organization (1985) 81·2% had impaired glucose tolerance and 18·8% gestational diabetes. Gestational diabetic women were of higher parity, more obese, required insulin therapy more often, had more babies weighing >4 kg and had higher fasting plasma glucose than women with impaired glucose tolerance. Women with gestational impaired glucose tolerance were older, of higher parity, more obese and had heavier babies than pregnant women with a normal screening plasma glucose. Compared with women with impaired glucose tolerance, gestational diabetic women were more likely to have abnormality, and more severe impairment of their glucose tolerance test in the puerperium.
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OBJECTIVE To evaluate whether risk factors and changes in insulin concentrations differ in subjects who develop impaired glucose tolerance with or without weight gain. Hyperinsulinemia is a risk factor for impaired glucose tolerance, and insulin concentrations increase further with the development of impaired glucose tolerance. Its development, however, often is accompanied by weight gain, which, by itself, is associated with high insulin concentrations. RESEARCH DESIGN AND METHODS Participants for this study were adult Pima Indians involved in an ongoing epidemiological study. Initially, all had normal glucose tolerance. During follow-up, 80 of 387 who did not gain weight developed impaired glucose tolerance, as did 295 of 1026 who gained weight. Risk factors for impaired glucose tolerance and the relationships between changes in weight and glucose and changes in insulin were evaluated by multivariate analyses. RESULTS High baseline fasting insulin predicted impaired glucose tolerance regardless of weight after adjustment for age, sex, body mass index, and glucose. The development of impaired glucose tolerance was accompanied by a further increase in fasting and 2-h insulin, whether or not subjects gained weight. In both weight-change groups, impaired glucose tolerance was associated with more centralized fat distribution. CONCLUSIONS Fasting hyperinsulinemia, a reflection of insulin resistance, is associated with the risk of developing impaired glucose tolerance whether or not weight is gained. Impaired glucose tolerance occurs when insulin resistance increases further. Weight gain is the most common precipitating factor. Aging and physical inactivity are other possible precipitating factors.
Hyperinsulinemia
Glucose tolerance test
Impaired fasting glucose
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The present study compared the relative tolerance to honey and glucose of subjects with impaired glucose tolerance or mild diabetes. Thirty individuals 35–60 years old with a proven parental (mother or father) history of type II diabetes mellitus were subjected simultaneously to an oral glucose tolerance test (GTT) and a honey tolerance test (HTT). Glucose tolerance was found to be impaired in 24 subjects, while six of the subjects were diagnosed as mildly diabetic. All subjects with impaired glucose tolerance exhibited significantly lower plasma glucose concentrations after consumption of honey at all time points of the HTT in comparison to the GTT. The plasma glucose levels in response to honey peaked at 30–60 minutes and showed a rapid decline as compared to that to glucose. Significantly, the high degree of tolerance to honey was recorded in subjects with diabetes as well, indicating a lower glycemic index of honey. Thus, it is evident from the present investigation that honey may prove to be a valuable sugar substitute for subjects with impaired glucose tolerance or mild diabetes.
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In a group of 51 women who had given birth to giant children, the glucose tolerance test (GTT) was performed at entry in the study and after intervals of 6 to 12 years. The results of the first determination, estimated according to the WHO's criteria (1980), have revealed an impaired glucose tolerance (IGT) in 7 cases (14%); the second determination showed IGT in 10 cases (20%) and diabetes mellitus in 2 (4%). Insulinemia assays, concomitant with the second performance of GTT, showed the highest values in the diabetic subjects, moderate values in those with IGT, and low values in those with normal glucose tolerance. The presence of obesity in some cases could not be considered as fully responsible for the glucose tolerance impairment in the women with fetal gigantism. The dynamics of glucose tolerance disorders showed variations in time, i.e. the initial pathologic changes were no more recorded on the second testing in the same subjects, while women with normal initial GTT showed high insulinemia or IGT on the second determination.
Gigantism
Glucose tolerance test
Concomitant
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The author investigated the development of abnormalities in the glucose tolerance in 70 subjects, 36 men and 34 women, where both parents were type II diabetics. The mean age of the offspring was 35.2 +/- 7.4 years, the mean follow up period 8.7 +/- 3.9 years. In the present work the blood glucose level and serum insulin after an oral glucose tolerance test are evaluated and compared with the results of tests of a matched control group of 37 healthy subjects without a family-history of diabetes. Based on repeated examinations the group was divided into sub-groups: with a repeatedly normal glucose tolerance (38%) and sub-groups where at least once a borderline glucose tolerance was recorded (19%), or impaired glucose tolerance (24%) and diabetes (19%). These abnormalities developed variably and were associated with an increased and delayed insulin secretion. Insulin resistance developed. A significant difference was found in the blood glucose levels during the initial normal test among offspring with a repeatedly normal glucose tolerance and offspring who changed from normal glucose tolerance to impaired glucose tolerance and diabetes. From the prognostic aspect the blood glucose level two hours after glucose administration was most valuable.
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