The "metabolic syndrome" is less useful than random plasma glucose to screen for glucose intolerance

Systematic Review and Meta-Analysis of Response Rates and Diagnostic Yield of Screening for Type 2 Diabetes and Those at High Risk of Diabetes

Background

Screening for type 2 diabetes (T2DM) and individuals at risk of diabetes has been advocated, yet information on the response rate and diagnostic yield of different screening strategies are lacking.

Methods

Studies (from 1998 to March/2015) were identified through Medline, Embase and the Cochrane library and included if they used oral glucose tolerance test (OGTT) and WHO-1998 diagnostic criteria for screening in a community setting. Studies were one-step strategy if participants were invited directly for OGTT and two, three/four step if participants were screened at one or more levels prior to invitation to OGTT. The response rate and diagnostic yield were pooled using Bayesian random-effect meta-analyses.

Findings

47 studies (422754 participants); 29 one-step, 11 two-step and seven three/four-step were identified. Pooled response rate (95% Credible Interval) for invitation to OGTT was 65.5% (53.7, 75.6), 63.1% (44.0, 76.8), and 85.4% (76.4, 93.3) in one, two and three/four-step studies respectively. T2DM yield was 6.6% (5.3, 7.8), 13.1% (4.3, 30.9) and 27.9% (8.6, 66.3) for one, two and three/four-step strategies respectively. The number needed to invite to the OGTT to detect one case of T2DM was 15, 7.6 and 3.6 in one, two, and three/four-step strategies. In two step strategies, there was no difference between the response or yield rates whether the first step was blood test or risk-score. There was evidence of substantial heterogeneity in rates across study populations but this was not explained by the method of invitation, study location (rural versus urban) and developmental index of the country in which the study was performed.

Conclusions

Irrespective of the invitation method, developmental status of the countries and or rural/urban location, using a multi-step strategy increases the initial response rate to the invitation to screening for diabetes and reduces the number needed to have the final diagnostic test (OGTT in this study) for a definite diagnosis.

A novel test for IGT utilizing metabolite markers of glucose tolerance

The oral glucose tolerance test (OGTT) is the only method to diagnose patients having impaired glucose tolerance (IGT), but its use has diminished considerably in recent years. Metabolomic profiling studies have identified a number of metabolites whose fasting levels are associated with dysglycemia and type 2 diabetes. These metabolites may serve as the basis of an alternative test for IGT. Using the stable isotope dilution technique, quantitative assays were developed for 23 candidate biomarker metabolites. These metabolites were measured in fasting plasma samples taken just prior to an OGTT from 1623 nondiabetic subjects: 955 from the Relationship between Insulin Sensitivity and Cardiovascular Disease Study (RISC Study; 11.7% IGT) and 668 subjects from the Diabetes Mellitus and Vascular Health Initiative (DMVhi) cohort from the DEXLIFE project (11.8% IGT). The associations between metabolites, anthropometric, and metabolic parameters and 2hPG values were assessed by Pearson correlation coefficients and Random Forest classification analysis to rank variables for their ability to distinguish IGT from normal glucose tolerance (NGT). Multivariate logistic regression models for estimating risk of IGT were developed and evaluated using AUCs calculated from the corresponding ROC curves. A model based on the fasting plasma levels of glucose, α-hydroxybutyric acid, β-hydroxybutyric acid, 4-methyl-2-oxopentanoic acid, linoleoylglycerophosphocholine, oleic acid, serine and vitamin B5 was optimized in the RISC cohort (AUC = 0.82) and validated in the DMVhi cohort (AUC = 0.83). A novel, all-metabolite-based test is shown to be a discriminate marker of IGT. It requires only a single fasted blood draw and may serve as a more convenient surrogate for the OGTT or as a means of identifying subjects likely to be IGT.

Diagnostic performance of 2 h postprandial capillary and venous glucose as a screening test for abnormal glucose tolerance

AIMS

To evaluate the diagnostic performance of postprandial venous and capillary glucose to screen for abnormal glucose tolerance in primary care setting.

METHODS

Both post-breakfast venous plasma and capillary blood glucose were taken simultaneously from a consecutive sample of volunteer civil service workers in Khon Kaen, Thailand between June and December 2009. The 75-g oral glucose tolerance test was performed within 3 days of the baseline visit. Both postprandial capillary and venous glucose were assessed for sensitivity, specificity, area under the receiver operating characteristic (ROC) curve and likelihood ratio using the oral glucose tolerance test (OGTT) results for the diagnosis of abnormal glucose tolerance as a gold standard.

RESULTS

1102 volunteers participated, of whom 874 (79.3%) completed the full study protocol. Five-hundred and four (57.8%) of 874 participants were female. The mean age was 39.9 years (SD=12.16) and the mean BMI was 24.3 kg/m(2) (SD=6.86). The sensitivity and specificity at the optimal cut-off point for venous glucose were 68.28% (95% CI 60.04-75.75) and 67.90% (95% CI 64.38-71.28), respectively. The sensitivity and specificity at the optimal cut-off point for capillary glucose were 63.45% (95% CI 55.05-71.28) and 64.06% (95% CI 60.46-67.55), respectively. The area under the ROC curve was 0.73 (95% CI 0.68-0.78) for venous glucose and 0.69 (95% CI 0.64-0.74) for capillary glucose. The subgroup analysis involving individuals with waist circumference>90 cm improved the area under the curve (AUC) to 0.76 (95% CI 0.68-0.83).

CONCLUSIONS

Postprandial blood glucose testing had a moderate discriminating characteristic for the diagnosis of abnormal glucose tolerance. Careful consideration is needed when using it to screen for this condition in general population.

Metabolic syndrome, impaired fasting glucose and obesity, as predictors of incident diabetes in 14 120 hypertensive patients of ASCOT-BPLA: comparison of their relative predictability using a novel approach

AIMS

To evaluate, in hypertensive patients, whether the metabolic syndrome is a better predictor of new-onset diabetes compared with impaired fasting glucose, obesity or its other individual components alone, or collectively.

METHODS

Cox models were developed to assess the risk of new-onset diabetes associated with the metabolic syndrome after adjusting for a priori confounders (age, sex, ethnicity and concomitant use of non-cardiovascular medications), its individual components and other determinants of new-onset diabetes. Area under receiver operator curves using the metabolic syndrome or models of impaired fasting glucose were compared, and the ability of these models to correctly identify those who (after 5-years of follow-up) would or would not develop diabetes was assessed.

RESULTS

The metabolic syndrome adjusted for a priori confounders and its individual components, and further adjusted for other determinants, was associated with significantly increased risk of new-onset diabetes [1.19 (1.00-1.40), P = 0.05 and 1.22 (1.03-1.44), P = 0.02, respectively]. The discriminative ability of the metabolic syndrome model [area under receiver operating curve: 0.764 (0.750-0.778)] was significantly better than the model of impaired fasting glucose [0.742 (0.727-0.757)] (P < 0.001). The metabolic syndrome correctly allocates the risk of new-onset diabetes in a significantly higher proportion of patients (62.3%) than impaired fasting glucose status (37.7%) (P < 0.001). The presence of both the metabolic syndrome and impaired fasting glucose were associated with an approximately 9-fold (7.47-10.45) increased risk of new-onset diabetes. Among normoglycaemic patients, the metabolic syndrome was also associated with significantly increased risk of new-onset diabetes, after adjusting for BMI and a priori confounders [1.66 (1.29-2.13)].

CONCLUSIONS

Both impaired fasting glucose and the metabolic syndrome predict the risk of new-onset diabetes; however, the metabolic syndrome is a better predictor than impaired fasting glucose in assigning the risk of new-onset diabetes in hypertensive patients, and among those with normoglycaemia.

Distribution of hyperglycaemia and related cardiovascular disease risk factors in low-income countries: a cross-sectional population-based survey in rural Uganda

BACKGROUND

Data on non-communicable disease (NCD) burden are often limited in developing countries in Africa but crucial for planning and implementation of prevention and control strategies. We assessed the prevalence of related cardiovascular disease risk factors (hyperglycaemia, high blood pressure and obesity) in a longstanding population cohort in rural Uganda.

METHODS

Trained field staff conducted a cross-sectional population-based survey of cardiovascular disease risk indicators using a questionnaire and simple measurements of body mass index (BMI), waist and hip circumference, waist/hip ratio (WHR), blood pressure and random plasma glucose. All members of the population cohort aged ≥13 years were eligible to participate in the survey.

RESULTS

Of the 4801 males and 5372 females who were eligible, 2719 (56.6%) males and 3959 (73.7%) females participated in the survey. Male and female participants had a mean standard deviation (SD) age of 31.8 (18.4) years and 33.7 (17.6) years, respectively. The observed prevalences of probable diabetes (glucose >11.0 mmol/l) and probable hyperglycaemia (7.0-11.0 mmol/l) were 0.4 and 2.9%, respectively. Less than 1% of males and 4% of females were obese (BMI ≥30 kg/m(2)), with 3.6% of males and 14.5% of females being overweight (BMI 25.0-29.9 kg/m(2)). However, in women, the prevalence of abdominal obesity was high (71.3% as measured by WHR and 31.2% as measured by waist circumference). The proportions of male and female current regular smokers were low (13.7 and 0.9%, respectively). The commonest cardiovascular disease risk factor was high blood pressure, with an observed prevalence of 22.5% in both sexes.

CONCLUSIONS

Population-based data on the burden of related cardiovascular disease risk factors can aid in the planning and implementation of an effective response to the double burden of communicable diseases and NCDs in this rural population of a low-income country undergoing epidemiological transition.

Lifestyle Interventions and the Prevention and Treatment of Type 2 Diabetes

The diabetes epidemic is fueled by a societal increase in insulin resistance, caused by lifestyle factors, particularly excessive caloric intake and physical inactivity. Aging also plays a role in the increase in insulin resistance; however, even in older populations, the increase in insulin resistance appears to be attributable mainly to age-related obesity and inactivity. Insulin resistance reflects deposition of visceral, hepatic, and intramyocellular fat, while toxic messages from the adipose organ (free fatty acids, cytokines, and oxidative stress) impair insulin action to restrain glucose production in the liver and promote glucose disposal in muscle. Unexercised muscle is also insulin resistant because of intracellular sequestration of glucose transporters. These processes lead to hyperglycemia if compensatory secretion of insulin is inadequate due to decreases in pancreatic β -cell function and mass, ultimately resulting in the development of prediabetes and, later, type 2 diabetes mellitus (T2DM). Lifestyle interventions, programs that promote diabetes risk reduction and weight loss through behavior change, increased physical activity, and dietary modification, can decrease insulin resistance and prevent or delay the development of prediabetes and progression to T2DM. Lifestyle interventions are also important to improve diabetes management, particularly early in the natural history before loss of β -cell function and mass is so extensive that multidrug pharmacologic therapy is required. Effective interventions often include both an increase in physical activity (ideally, at least 150 minutes per week of moderate-to-vigorous aerobic exercise and strength training) and dietary modification to promote weight loss. major contributor to morbidity and mortality. T2DM can lead to renal dysfunction, peripheral and autonomic neuropathy, vision problems, and cardiovascular disease.2 In the United States alone, from 2005 to 2050, the prevalence of diagnosed diabetes is expected to more than double from 5.6% to 12.0%.3 In 2005 to 2006, the prevalence of prediabetes and diabetes combined was estimated to be 42.3% for Americans aged 20 years or older. The total prevalence of