Impaired glucose tolerance

Infrared Spectroscopy for Rapid Triage of Cancer Using Blood Derivatives: A Reality Check

Infrared (IR) spectroscopy of serum/plasma represents an alluring molecular diagnostic tool, especially for cancer, as it can provide a molecular fingerprint of clinical samples based on vibrational modes of chemical bonds. However, despite the superior performance, the routine adoption of this technique for clinical settings has remained elusive. This is due to the potential confounding factors that are often overlooked and pose a significant barrier to clinical translation. In this Perspective, we summarize the concerns associated with various confounding factors, such as fluid sampling, optical effects, hemolysis, abnormal cardiovascular and/or hepatic functions, infections, alcoholism, diet style, age, and gender of a patient or normal control cohort, and improper selection of numerical methods that ultimately would lead to improper spectral diagnosis. We also propose some precautionary measures to overcome the challenges associated with these confounding factors.

High 1-h glucose in youths with obesity as marker of prediabetes and cardiovascular risk

PURPOSE

Testing 1-h glucose (1HG) concentration during oral glucose tolerance test is cost-effective to identify individuals at risk of incident type 2 diabetes. Aim of the study was to define 1HG cutoffs diagnostic of incident impaired glucose tolerance (IGT) in youths with obesity, and to evaluate prevalence and association of cutoffs identified in the cohort and from the literature (133 and 155 mg/dl) to cardiovascular disease (CVD) in a population of youths with obesity.

METHODS

This is a longitudinal study of 154 youths to identify 1HG cutoffs, and cross-sectional study of 2295 youths to estimate prevalence of high 1HG and association to CVD. Receiver-operating characteristic curves (ROC) were used to establish 1HG cutoffs, and univariate regression analyses to test association of 1HG to blood pressure, lipids and aminotransferases.

RESULTS

ROC analysis identified the 1HG cutoff of 159 mg/dl as having diagnostic accuracy of IGT with area under the ROC 0.82 (95% CI 0.66-0.98), sensitivity 0.86% and specificity 0.79%. In the cross-sectional population, prevalence of high 1HG was 36% and 15% for 133 and 155 mg/dl cutoffs, respectively, and 17% for the 159 mg/dl value. All the examined cutoffs were significantly associated with worse lipid profile, liver function test, reduced insulin sensitivity, secretion and disposition index.

CONCLUSION

High 1HG is marker of persistent IGT and increased risk of metabolic abnormalities in youths. The 155 mg/dl cutoff is a convenient estimate in young people but longitudinal studies with retinopathy and overt diabetes as end points are advised to verify the 1HG cutoff with the best diagnostic accuracy.

Reproducibility of Glycemic Measures Among Dysglycemic Youth and Adults in the RISE Study

AIMS

Previous work found poor reproducibility for measures of glycemia in individuals at risk for dysglycemia. Differences between youth and adults have not been assessed. Using youth and adults in the Restoring Insulin Secretion Study, we tested variability and classification concordance for hemoglobin A1C (HbA1c), fasting and 2-hour glucose from oral glucose tolerance tests (OGTTs).

METHODS

HbA1c and glucose on repeated samples obtained ∼6 weeks apart were compared in 66 youth (mean age 14.2 years) and 354 adults (52.7 years). Changes, coefficient of variation (CV), and concordance of diagnostic categories between the 2 visits were compared.

RESULTS

Mean difference between the 2 visits in HbA1c was higher in youth than adults (P < .001), while fasting glucose was similar and 2-hour glucose was lower in youth (P = .051). CV was smallest for HbA1c compared to fasting and 2-hour glucose. For HbA1c, youth had higher CV (P < .001); whereas CV for 2-hour glucose was lower for youth (P = .041). Classification concordance by HbA1c was lower in youth (P = .004). Using OGTT or HbA1c for classification, intervisit variability produced discordant classification in 20% of youth and 28% of adults. Using both fasting glucose and HbA1c, intervisit variability reduced discordant classification to 16% of adults while not improving classification in youth.

CONCLUSIONS

Poor reproducibility and lack of classification concordance highlight the limitations of one-time testing, with important implications for assessing eligibility in clinical trials. Consideration should be given to using more than a single parameter for screening and diagnosis, especially when classification category is important.

Management of Diabetes in People Undergoing Dental Treatment in Primary Care

Diabetes mellitus is a condition resulting from loss of production of insulin, or insufficient production/insulin resistance leading to high blood glucose levels. Management of the condition can be provided in a variety of settings and is tailored to the person's requirements. The condition has a lifelong, systemic impact due to microvascular and macrovascular complications. Diabetes mellitus has dental implications due to increased risk of infections, poor wound healing, rapid progression of periapical pathology, xerostomia, burning mouth syndrome, and a bidirectional link with periodontal disease. Two clinical cases of patients with diabetes are discussed and their dental management described. Many people with diabetes can be treated in primary care, however, some with suboptimal glycaemic control may require specialist input and liaison with the patient's diabetes team.

Is it necessary to screen patient with adhesive capsulitis of shoulder for diabetes mellitus?

BACKGROUND

Idiopathic adhesive capsulitis of shoulder is common cause of pain and restriction of shoulder motion between the ages of 30 and 65. The prevalence of adhesive capsulitis is as high as 10% to 22% in diabetes mellitus as compared normal population which is 02% and 04%. Therefore, the doubt arises whether patients developed adhesive capsulitis are at greater risk to develop diabetes mellitus and should be screen for diabetes so that it can be detected early.

PURPOSE

To compare the prevalence of prediabeties and diabetes mellitus among patients with features of idiopathic adhesive capsulitis of shoulder who are otherwise healthy.

METHODS

Patients between 30-65 years of age who attended Orthopaedics OPD with features of idiopathic adhesive capsulitis of shoulder were included. Participated underwent a 2 hour long oral glucose tolerance test and based on fasting and 2-hour plasma glucose levels, patients were diagnosed as normal glucose tolerance, prediabetic, or diabetic and the results were matched with previous published data.

RESULTS

135 patients as participated and completed the test. 21 (15.5%) patients with idiopathic adhesive capsulitis of shoulder were found to be prediabetic, and 37 (27.4%) patients were found to be diabetic. However, 31 patients had family history of diabetes.

CONCLUSION

Based on our study, we can recommend that patients with features of idiopathic adhesive capsulitis of shoulder should be screened at least for fasting and post prandial blood sugar so that diabetes can be detected early.

Incidence of new diabetes following CABG surgery: Analysis of a single centre registry data

BACKGROUND

About 40-50% of patients undergoing coronary artery bypass graft (CABG) surgery have diabetes. The prevalence of impaired glucose tolerance (IGT) is also high in this group, however, incidence of new diabetes following CABG surgery is unknown.

OBJECTIVES

To determine incidence of new diabetes and the impact on ICU and hospital stay in patients undergoing CABG surgery in India, we performed a registry-based study.

METHODS

Prospectively collected data among consecutive adult cardiac surgical patients who underwent CABG surgery at a single hospital were analyzed. Descriptive statistics are reported.

RESULTS

We recruited 1559 consecutive patients (men 1355, women 204) and analyzed data among 933 non-diabetic patients. Patients with known diabetes (n = 626, 40%) were excluded. 57 (6.1%) of the 933 non-diabetic patients developed persistently high glucose levels at discharge with incidence rate of 61 + 5/1000. Patients who developed diabetes had similar age and body mass index vs those who did not, but had greater preoperative IGT (44.6 vs 13.7%) and more time-period in intensive care unit (102.0 + 75 vs 80.2 + 29 hours) as well as in hospital (11.7 + 5.7 vs 9.6 + 2.4 days) (p < 0.001).

CONCLUSION

In a significant proportion of non-diabetic patients diabetes is unmasked after CABG. This is more likely in those with impaired glucose tolerance and prolonged period in intensive care and hospital.

Development of type 2 diabetes mellitus in people with intermediate hyperglycaemia

BACKGROUND

Intermediate hyperglycaemia (IH) is characterised by one or more measurements of elevated blood glucose concentrations, such as impaired fasting glucose (IFG), impaired glucose tolerance (IGT) and elevated glycosylated haemoglobin A1c (HbA1c). These levels are higher than normal but below the diagnostic threshold for type 2 diabetes mellitus (T2DM). The reduced threshold of 5.6 mmol/L (100 mg/dL) fasting plasma glucose (FPG) for defining IFG, introduced by the American Diabetes Association (ADA) in 2003, substantially increased the prevalence of IFG. Likewise, the lowering of the HbA1c threshold from 6.0% to 5.7% by the ADA in 2010 could potentially have significant medical, public health and socioeconomic impacts.

OBJECTIVES

To assess the overall prognosis of people with IH for developing T2DM, regression from IH to normoglycaemia and the difference in T2DM incidence in people with IH versus people with normoglycaemia.

SEARCH METHODS

We searched MEDLINE, Embase, ClincialTrials.gov and the International Clinical Trials Registry Platform (ICTRP) Search Portal up to December 2016 and updated the MEDLINE search in February 2018. We used several complementary search methods in addition to a Boolean search based on analytical text mining.

SELECTION CRITERIA

We included prospective cohort studies investigating the development of T2DM in people with IH. We used standard definitions of IH as described by the ADA or World Health Organization (WHO). We excluded intervention trials and studies on cohorts with additional comorbidities at baseline, studies with missing data on the transition from IH to T2DM, and studies where T2DM incidence was evaluated by documents or self-report only.

DATA COLLECTION AND ANALYSIS

One review author extracted study characteristics, and a second author checked the extracted data. We used a tailored version of the Quality In Prognosis Studies (QUIPS) tool for assessing risk of bias. We pooled incidence and incidence rate ratios (IRR) using a random-effects model to account for between-study heterogeneity. To meta-analyse incidence data, we used a method for pooling proportions. For hazard ratios (HR) and odds ratios (OR) of IH versus normoglycaemia, reported with 95% confidence intervals (CI), we obtained standard errors from these CIs and performed random-effects meta-analyses using the generic inverse-variance method. We used multivariable HRs and the model with the greatest number of covariates. We evaluated the certainty of the evidence with an adapted version of the GRADE framework.

MAIN RESULTS

We included 103 prospective cohort studies. The studies mainly defined IH by IFG5.6 (FPG mmol/L 5.6 to 6.9 mmol/L or 100 mg/dL to 125 mg/dL), IFG6.1 (FPG 6.1 mmol/L to 6.9 mmol/L or 110 mg/dL to 125 mg/dL), IGT (plasma glucose 7.8 mmol/L to 11.1 mmol/L or 140 mg/dL to 199 mg/dL two hours after a 75 g glucose load on the oral glucose tolerance test, combined IFG and IGT (IFG/IGT), and elevated HbA1c (HbA1c5.7: HbA1c 5.7% to 6.4% or 39 mmol/mol to 46 mmol/mol; HbA1c6.0: HbA1c 6.0% to 6.4% or 42 mmol/mol to 46 mmol/mol). The follow-up period ranged from 1 to 24 years. Ninety-three studies evaluated the overall prognosis of people with IH measured by cumulative T2DM incidence, and 52 studies evaluated glycaemic status as a prognostic factor for T2DM by comparing a cohort with IH to a cohort with normoglycaemia. Participants were of Australian, European or North American origin in 41 studies; Latin American in 7; Asian or Middle Eastern in 50; and Islanders or American Indians in 5. Six studies included children and/or adolescents.Cumulative incidence of T2DM associated with IFG5.6, IFG6.1, IGT and the combination of IFG/IGT increased with length of follow-up. Cumulative incidence was highest with IFG/IGT, followed by IGT, IFG6.1 and IFG5.6. Limited data showed a higher T2DM incidence associated with HbA1c6.0 compared to HbA1c5.7. We rated the evidence for overall prognosis as of moderate certainty because of imprecision (wide CIs in most studies). In the 47 studies reporting restitution of normoglycaemia, regression ranged from 33% to 59% within one to five years follow-up, and from 17% to 42% for 6 to 11 years of follow-up (moderate-certainty evidence).Studies evaluating the prognostic effect of IH versus normoglycaemia reported different effect measures (HRs, IRRs and ORs). Overall, the effect measures all indicated an elevated risk of T2DM at 1 to 24 years of follow-up. Taking into account the long-term follow-up of cohort studies, estimation of HRs for time-dependent events like T2DM incidence appeared most reliable. The pooled HR and the number of studies and participants for different IH definitions as compared to normoglycaemia were: IFG5.6: HR 4.32 (95% CI 2.61 to 7.12), 8 studies, 9017 participants; IFG6.1: HR 5.47 (95% CI 3.50 to 8.54), 9 studies, 2818 participants; IGT: HR 3.61 (95% CI 2.31 to 5.64), 5 studies, 4010 participants; IFG and IGT: HR 6.90 (95% CI 4.15 to 11.45), 5 studies, 1038 participants; HbA1c5.7: HR 5.55 (95% CI 2.77 to 11.12), 4 studies, 5223 participants; HbA1c6.0: HR 10.10 (95% CI 3.59 to 28.43), 6 studies, 4532 participants. In subgroup analyses, there was no clear pattern of differences between geographic regions. We downgraded the evidence for the prognostic effect of IH versus normoglycaemia to low-certainty evidence due to study limitations because many studies did not adequately adjust for confounders. Imprecision and inconsistency required further downgrading due to wide 95% CIs and wide 95% prediction intervals (sometimes ranging from negative to positive prognostic factor to outcome associations), respectively.This evidence is up to date as of 26 February 2018.

AUTHORS' CONCLUSIONS

Overall prognosis of people with IH worsened over time. T2DM cumulative incidence generally increased over the course of follow-up but varied with IH definition. Regression from IH to normoglycaemia decreased over time but was observed even after 11 years of follow-up. The risk of developing T2DM when comparing IH with normoglycaemia at baseline varied by IH definition. Taking into consideration the uncertainty of the available evidence, as well as the fluctuating stages of normoglycaemia, IH and T2DM, which may transition from one stage to another in both directions even after years of follow-up, practitioners should be careful about the potential implications of any active intervention for people 'diagnosed' with IH.

Inside out the Ragbag of Glucose Intolerance in Obese Adolescents

BACKGROUND/AIMS

The prevalence of impaired glucose tolerance (IGT) is rising among obese adolescents in parallel with epidemic obesity. In some cases, IGT reverts to normal glucose tolerance (NGT) by the end of puberty. The aims of the present study were to investigate metabolic factors determining changes over time of glucose at 120 min (Glu120) following an oral glucose tolerance test (OGTT), and to verify whether preserved β-cell glucose sensitivity (βCGS) protects against persistent IGT.

METHODS

We performed a cohort study of 153 severely obese children and adolescents evaluated with a 5-point OGTT at baseline and at follow-up with measurements of glucose, insulin, and C-peptide to estimate several empirical parameters of insulin sensitivity (includ ing oral glucose insulin sensitivity [OGIS] and OGTT-derived glucose effectiveness) and secretion.

RESULTS

At follow-up (range 0.9-4.8 year), 113 (73.9%) patients remained with NGT, 9 (5.9%) had IGT, and 28 (18.3%) had reverted to NGT; 3 NGT patients had developed IGT. In multivariable models, change in loge(βCGS) was inversely associated with time-related change in loge(Glu120), with (model 2) and without (model 1) correction for the change in loge(OGIS). Model 2 was more strongly associated with change in loge(Glu120).

CONCLUSIONS

Changes in βCGS and insulin sensitivity were inversely associated with changes in Glu120 at follow-up, contributing a likely explanation for the reversal of IGT to NGT.

Should Patients With Frozen Shoulder Be Screened for Diabetes Mellitus?

Background:

Idiopathic frozen shoulder (nontraumatic) is commonly encountered in patients between the ages of 35 and 60 years in general orthopaedic practice. While the prevalence of frozen shoulder among the general population is estimated to be between 2% and 4%, a significantly higher prevalence of 10% to 22% has been reported in patients with diabetes mellitus. Since diabetic patients are more prone to develop frozen shoulder than nondiabetics, the question arises as to whether patients diagnosed as having idiopathic frozen shoulder are at greater risk to develop diabetes mellitus and should be routinely screened for this condition.

Purpose:

To compare the prevalence of diabetes mellitus and prediabetes among patients diagnosed with idiopathic frozen shoulder who are not known to have either diabetes mellitus or prediabetic conditions with that of an age-matched group from the general population.

Study Design:

Case series; Level of evidence, 4.

Methods:

Patients at a shoulder clinic with a diagnosis of idiopathic frozen shoulder were asked to participate in the study if they were aged between 35 to 60 years and had no known previous diagnosis of diabetes mellitus or prediabetic conditions. These patients underwent a 2-hour oral glucose tolerance test. According to their fasting and 2-hour plasma glucose levels, patients were diagnosed as normal glucose tolerance, prediabetic, or diabetic. Findings were matched with the prevalence in an age-matched general population.

Results:

Fifty patients completed the test. Four patients with idiopathic frozen shoulder (8%) were found to be prediabetic. No patient was found to be diabetic. All 4 patients reported a history of diabetes in their parents or siblings.

Conclusion:

Patients diagnosed with idiopathic frozen shoulder who are 60 years or younger and are not known diabetics have a similar probability of having diabetes or prediabetes to an age-matched population. No routine diabetic workup is warranted specifically for these patients.

The Diabetes Prevention Program: headline results

The Diabetes Prevention Program (DPP) was a trial of over 3,000 people with impaired glucose tolerance (IGT) to assess the effect of different interventions on their progression to type 2 diabetes. During an average follow-up period of three years, intensive lifestyle intervention with regular exercise and weight loss reduced the risk of progression to type 2 diabetes by 58%. Treatment with the antihyperglycaemic agent metformin reduced progression to type 2 diabetes by 31%. The DPP has therefore confirmed that rigorous lifestyle management can reduce the risk of type 2 diabetes and also shown that metformin therapy can reduce diabetes risk.

Change in daily ambulatory activity and cardiovascular events in people with impaired glucose tolerance

Patients with pre-diabetes have a tenfold higher risk of developing Type 2 DM and a twofold higher risk of developing coronary heart disease compared to non-diabetics. Interventions targeted at those in an early stage of impaired glucose metabolism can delay or prevent diabetes. Effects of these interventions on cardiovascular outcome are unknown. This article aims to review current and available data on lifestyle intervention, specifically physical activity, on cardiovascular outcomes in populations at risk for diabetes. We searched PubMed database from 1990 to present with focus on more recent literature published over the last 2 years. Various permutations of keywords used included glucose intolerance, pre-diabetes, diabetes, lifestyle modifications, physical activity, and cardiovascular disease. Intensive glycemic control, specific medications, and lifestyle intervention including increase in physical activity have been evaluated in diabetes and pre-diabetes. Most studies we reviewed showed that these interventions prevented progression of pre-diabetes to diabetes and improved cardiovascular risk surrogate measures. Direct decrease in cardiovascular mortality, non-fatal stroke, and non-fatal myocardial infarctions was shown in one recent trial. Increase in physical activity has a positive effect on decreasing cardiovascular risk by modifying several important risk factors and may decrease risk of events in pre-diabetics. More randomized high power trials are needed to verify and characterize these effects.

Variability of glucose-lowering effect as a limiting factor in optimizing basal insulin therapy: a review

Lowering blood glucose with insulin therapy towards beneficial target levels while also avoiding hypoglycaemia is a challenging task. An important confounding factor, which might be under-appreciated in this scenario, is that of variable glucose readings causing difficulties with dose adjustment. Furthermore, this glucose variability is, to some extent, a reflection of variability in the glucose-lowering action of the insulin therapy itself. Not only is glucose variability a major confounding factor in disease management but it is possibly also of direct prognostic consequence and is increasingly recognized as an informative measurement in diabetes management. The scope for insulin-induced glucose variability is particularly great with basal insulins because of their prolonged absorption from high-dose depots. Pharmacodynamic (PD) variability manifests as both fluctuations in the level of glucose-lowering effect over time, and as inconsistencies in the response from one injection to another. Well-controlled pharmacokinetic (PK)/PD studies using repeated isoglycaemic clamp methodology clearly how that many injected basal insulin products have high variable absorption with correspondingly variable action. Incomplete resuspension and precipitation appear to be important issues with regard to unpredictability in this action, while an inadequate duration of action relative to the dosing interval results in a fluctuating action profile. There are some ultra-long-acting basal insulins with novel protraction mechanisms currently in clinical development for which clamp studies show markedly improved PK/PD profiles.

Increased Leisure-Time Physical Activity is Associated With Lower Prevalence of the Metabolic Syndrome in 64-Year Old Women With Impaired Glucose Tolerance

The metabolic syndrome (MetS) is characterized by a cluster of factors that confer an increased risk of cardiovascular morbidity as well as mortality. It is established that physical activity (PA) has a protective role in cardiovascular morbidity and mortality, mainly through favorable effects on traditional risk factors such as body mass and blood pressure. We assessed the prevalence of MetS in a population-based sample of 64-year-old women with impaired glucose tolerance (IGT) with respect to leisure-time PA (LTPA). The results showed an inverse linear association ( P < .05) between LTPA and MetS in this group. In conclusion, this study suggests that an increased PA level has an important role in preventing MetS in women with IGT.

Natural history and physiological determinants of changes in glucose tolerance in a non-diabetic population: the RISC Study

AIMS/HYPOTHESIS

The natural history and physiological determinants of glucose intolerance in subjects living in Europe have not been investigated. The aim of this study was to increase our understanding of this area.

METHODS

We analysed the data from a population-based cohort of 1,048 non-diabetic, normotensive men and women (aged 30-60 years) in whom insulin sensitivity was measured by the glucose clamp technique (M/I index; average glucose infusion rate/steady-state insulin concentration) and beta cell function was estimated by mathematical modelling of the oral glucose tolerance test at baseline and 3 years later.

RESULTS

Seventy-seven per cent of the participants had normal glucose tolerance (NGT) and 5% were glucose intolerant both at baseline and follow up; glucose tolerance worsened in 13% (progressors) and improved in 6% (regressors). The metabolic phenotype of the latter three groups was similar (higher prevalence of familial diabetes, older age, higher waist-to-hip ratio, higher fasting and 2 h plasma glucose, higher fasting and 2 h plasma insulin, lower insulin sensitivity and reduced beta cell glucose sensitivity with increased absolute insulin secretion). Adjusting for these factors in a logistic model, progression was predicted by insulin resistance (bottom M/I quartile, OR 2.52 [95% CI 1.51-4.21]) and beta cell glucose insensitivity (bottom quartile, OR 2.39 [95% CI 1.6-3.93]) independently of waist-to-hip ratio (OR 1.44 [95% CI 1.13-1.84] for one SD). At follow up, insulin sensitivity and beta cell glucose sensitivity were unchanged in the stable NGT and stable non-NGT groups, worsened in progressors and improved in regressors.

CONCLUSIONS/INTERPRETATION

Glucose tolerance deteriorates over time in young, healthy Europids. Progressors, regressors and glucose-intolerant participants share a common baseline phenotype. Insulin sensitivity and beta cell glucose sensitivity predict and track changes in glucose tolerance independently of sex, age and obesity.

Abnormal glucose metabolism in non-diabetic patients presenting with an acute stroke: prospective study and systematic review

BACKGROUND

Non-diabetic patients presenting with an acute stroke often have hyperglycaemia. In most populations it is unknown whether the hyperglycaemia is transient and due to the acute stress response or whether it represents undiagnosed abnormal glucose metabolism.

AIM

To evaluate the prevalence and predictors of persistent hyperglycaemia in non-diabetic patients with an acute stroke.

DESIGN

Prospective observational study.

METHODS

Non-diabetic patients over 40 years old with an acute stroke were enrolled over a 2-year period. On admission patients were evaluated with an HbA(1c) and a 75 g oral glucose tolerance test (OGTT). The OGTT was repeated 3 months later. A meta-analysis was performed to interpret our results in the context of published data.

RESULTS

One hundred and seven patients were analysed. On admission 26 (24%) patients had diabetes, 39 (37%) had impaired glucose tolerance and 42 (39%) had normal glucose tolerance. Forty-four (68%) patients with hyperglycaemia on admission were re-investigated at least 3 months after discharge. Of these, 6 (14%) had diabetes, 12 (27%) had impaired glucose tolerance and 26 (59%) had normal glucose tolerance. A 2-h post-load glucose value >or=10 mmol/l predicted persistent hyperglycaemia with 72.2% sensitivity, 65.4% specificity and a positive predictive value and negative predictive value of 59.1 and 77.3%, respectively. A meta-analysis of prevalence data of impaired glucose metabolism in non-diabetic individuals 3 months after having had an acute stroke revealed a combined prevalence of 58% (95% confidence interval 25.4-90.5%).

CONCLUSION

In this study hyperglycaemia in the setting of an acute stroke was transient in the majority of patients.

Normalization of glucose intolerance in first-degree relatives of patients with type 2 diabetes

AIMS

The aim of this study was to estimate the conversion rate to normal glucose tolerance (NGT) from a state of abnormal glucose metabolism and to identify characteristics predicting the conversion rate in first-degree relatives (FDRs) of patients with type 2 diabetes with glucose intolerance.

METHODS

A total of 2368 (614 men and 1754 women) FDRs of consecutive patients with type 2 diabetes aged 20-70 years in 2003-2005 were followed through 2007. Glucose tolerance classification was based on the criteria of the American Diabetes Association base on standard 75 g 2-h oral glucose tolerance test. The study group consisted of 370 participants with glucose intolerance at baseline.

RESULTS

The conversion rates to normal glucose tolerance from impaired glucose tolerance (IGT) and impaired fasting glucose (IFG) were 16.2% (95% confidence interval (CI) 13.30, 19.10) and 10.9% (95% CI: 5.7, 16.1) per year after an average of 2 years, respectively. Lower baseline fasting plasma glucose (HR 1.02, 95% CI: 1.01, 1.04) and 2-h (HR 1.02, 95% CI: 1.01, 1.04) glucose predicted conversion to NGT, as did changes in body mass index (BMI), waist circumference (WC), and lipids.

CONCLUSIONS

This is the first estimate of conversion rate and predictors from IFG and IGT to NGT in FDRs of people with type 2 diabetes in Iran. Lower baseline fasting, 2-h plasma glucose and changes in BMI, WC, and lipids predicted reversal to NGT at 24 months follow-up.

Within-subject variability of measures of beta cell function derived from a 2 h OGTT: implications for research studies

AIMS/HYPOTHESIS

Knowledge of the within-subject variability of a parameter is required to properly design and calculate sample sizes for longitudinal studies. We sought to determine the day-to-day variability of measures of beta cell function derived from an OGTT.

METHODS

Thirty-seven adults (13 with normal glucose tolerance, ten with impaired glucose tolerance, 14 with type 2 diabetes) underwent a standard 2 h 75 g OGTT on two separate days (median time between tests, 7 days; range, 5-14). From these data, the reproducibility of several indices of beta cell function were determined: insulinogenic index (DeltaI(0-30)/DeltaG(0-30)), early C-peptide response (DeltaCP(0-30)/DeltaG(0-30)), incremental AUC insulin to glucose response (incAUC(ins)/incAUC(glu)), integrated insulin secretion response from 0 to 120 min (IS/Glu(0-120)) and indices of beta cell function derived from a mathematical model.

RESULTS

Within-subject variability for DeltaI(0-30)/DeltaG(0-30) (CV 57.1%) was higher than DeltaCP(0-30)/DeltaG(0-30) (CV 34.7%). Measures integrated over the full 120 min of the OGTT, incAUC(ins)/incAUC(glu) (CV 24.9%) and IS/Glu(0-120) (CV 17.4%), demonstrated less variability. The mathematical model-derived measures of beta cell glucose sensitivity (CV 20.3%) and potentiation (CV 33.0%) showed moderate variability. The impact of the different measures' variability on sample size (30% change from baseline) is demonstrated by calculated sample sizes of 89 for DeltaI(0-30)/DeltaG(0-30), 37 for DeltaCP(0-30)/DeltaG(0-30), 21 for incAUC(ins)/incAUC(glu) and 11 for IS/Glu(0-120).

CONCLUSIONS/INTERPRETATION

Some OGTT-derived indices of beta cell function, in particular the insulinogenic index, demonstrate high within-subject variability. Integrated measures that utilise multiple time points and measures that use C-peptide show less variability and may lead to a reduced sample size requirement.

Carbohydrate metabolism changes in cystic fibrosis

AIMS

To assess the prevalence of impaired glucose tolerance (ITG) and diabetes mellitus (DMRCF) in a group of patients with cystic fibrosis (CF). To study clinical status-related variables and to compare age with the evolution of their carbohydrate metabolism (CHM).

PATIENTS AND METHODS

Thirty patients with CF (1.5-26 years). Oral glucose tolerance test (OGTT) in 28 patients.

RESULTS

Three patients (10%) showed ITG and four DMRCF (13.3%). CF patients with impaired CHM (ICHM) were older (p = 0.006), and had longer times since diagnosis and first sputum colonization (p = 0.001, p < 0.001). Homozygous deltaF508 mutation was significant (p = 0.001). Insulin peak, area under the curve for insulin, insulin resistance, insulin sensitivity, and pancreatic beta-cell function were all significant.

CONCLUSIONS

ICHM was present in 23.3%. Age, time since diagnosis of CF, first sputum colonization and homozygous deltaF508 mutation were significantly associated. CHM in patients with CF is similar to that in the population without CF in the early years.

Predictive validity of different definitions of hypertension for type 2 diabetes

BACKGROUND

Models to predict diabetes or pre-diabetes often incorporate the assessment of hypertension, but proposed definitions for 'hypertension' are inconsistent. We compared the classifications obtained using different definitions for 'hypertension'.

METHODS

We compared records for 5158 cases from 181 family practices, who were later diagnosed with diabetes and prescribed oral hypoglycaemic drugs, with 5158 controls, matched for age, sex and family practice, who were never diagnosed with diabetes. We compared classifications obtained using definitions of hypertension based on medical diagnoses, prescription of blood pressure lowering drugs or both. We compared family practices where diagnosis or prescribing varied systematically.

RESULTS

Classification of hypertension based on recorded medical diagnoses gave a sensitivity of 32.2% for diabetes (95% confidence interval from 30.4 to 34.1%). Prescription of blood pressure lowering drugs in the 12 months before diagnosis gave a sensitivity of 47.2% (45.7 to 48.7%). Combining either a medical diagnosis or a blood pressure lowering prescription gave a sensitivity of 52.8% (51.3 to 54.3%). In family practices where hypertension was least frequently recorded, a diagnosis of hypertension gave a sensitivity of 19.5% for diabetes (17.4 to 21.6%) compared with 50.8% (46.3 to 55.3%) in the highest quintile. Prescription of blood pressure lowering drugs gave a sensitivity of 36.1% (33.1 to 39.0%) in the lowest prescribing practices but 58.2% (55.5 to 61.0%) in the highest quintile.

CONCLUSIONS

Misclassification errors depend on the definition of hypertension and its implementation in practice. Definitions of hypertension that depend on access or quality in health care should be avoided.

Development of impaired glucose tolerance and diabetes in follow-up offspring of Caribbean patients with type 2 diabetes: analysis of 5-year follow-up study

Several reports agreed that the antecedent markers for developing diabetes in offspring of type 2 diabetic patients involve excess body weight and insulin resistance. This study examined the pattern of changes in anthropometric and biochemical risk factors for developing diabetes in a follow-up offspring of Caribbean type 2 diabetic patients. Results of 46 offspring of type 2 diabetic patients who had received one-to-one individualized diet and exercise counseling for 5 years in our laboratory were analyzed. Changes in anthropometric (body weight, waist circumference) and biochemical (insulin, glucose, lipids, HOMA-insulin resistance, HOMA-percent beta-cell function) parameters over the 5-year period were analyzed using ANOVA tests. Of the 46 offspring, 10.9 and 2.2%, respectively, developed impaired glucose tolerance (IGT) and diabetes. Over the years, IGT offspring had a significant step-wise increase and decrease in fasting and 2-h postprandial plasma glucose levels (P < 0.05) and percent B-cell function (P < 0.001), respectively. Again, a non-significant step-wise increase was observed in body mass index, waist circumference and HOMA-insulin resistance levels (P > 0.05). While we await the results of medication-based intervention studies in different populations, exercise and diet counseling will remain the only available lifestyle intervention strategy for slowing IGT progression to diabetes.

Increased plasma levels of thioredoxin in patients with glucose intolerance

OBJECTIVE

The aim of the present study was to determine the effects of glucose intolerance on oxidative stress in patients with coronary artery disease (CAD).

METHODS

The patients were divided into 3 groups, diabetes mellitus (DM), IGT or normal glucose tolerance (NGT) according to the criteria of the American Diabetes Association.

PATIENTS

The present study consisted of 178 consecutive patients who underwent diagnostic coronary arteriography and a 75-g glucose tolerance test.

RESULTS

The level of plasma thioredoxin, a marker of oxidative stress was measured in every patient during the fasting state. The levels of plasma thioredoxin were significantly higher in the DM and IGT groups than the NGT group. Furthermore, we found that there was a positive association between thioredoxin levels and glycosylated hemoglobin (sigma=0.225, p=0.018). In multivariate logistic regression analysis, glucose intolerance (DM or IGT) was only independently associated with the high levels of thioredoxin. The levels of plasma thioredoxin were significantly higher in the CAD group compared to the non-CAD group. In multivariate logistic regression analysis, high levels of thioredoxin, male, age and hypertension were independently associated with the presence of CAD.

CONCLUSION

Glucose intolerance was associated with the high levels of thioredoxin. High levels of thioredoxin were related to the presence of CAD. The measurement of thioredoxin as the marker of oxidative stress may be useful for monitoring the development of the cardiovascular diseases.

Detecting type 2 diabetes by a single post-challenge blood sample

In the recent American Diabetes Association (ADA)/WHO recommendations, the oral glucose tolerance test (OGTT) was replaced by the measurement of a single fasting glucose concentration with a decision limit for the detection of type 2 diabetes mellitus (DM) reduced. This proposal, however, misses all cases of isolated post-prandial hyperglycaemia. Therefore, a study was undertaken to develop a post-challenge, one-sample mode of diagnosis. OGTT was performed in 240 high-risk subjects who were suspected to suffer from type 2 DM. Glucose concentrations were determined at 30 min intervals in the capillary blood, venous blood and plasma, and insulin was determined in venous plasma only. The test results were classified in non-disease and disease group according to the decision limits recommended by ADA/WHO. Furthermore, the early insulin response and an insulin sensitivity index were used to determine new cut-off values. These were identified as the concentrations demonstrating the highest diagnostic efficiency and were lower than the WHO limits. The 2 h post-load plasma concentration led to higher efficiency at a cut-off value of 9.0 mmol/l glucose (162 mg/dl) compared to concentrations of samples taken in the fasting state, at an earlier time of the OGTT, or in venous and capillary blood. Under this condition, 72 diabetic patients (35%) were detected in the study group (n = 207), whereas only 36 (17%) were found with one sample in the fasting state and 53 (26%) with two samples using the ADA/WHO criteria. Therefore, a single venous plasma sample taken after 2 h post-glucose challenge appeared to be most efficient for the early detection of DM.

The impaired hyperglycemic peak as an additional indicator of Type 2 Diabetes development is misdetected

Because there is not an optimal control for Type 2 diabetes mellitus (DM2), which encompasses about 90% of diagnosed diabetic patients, its prevention is key. Early detection of DM2 development can be made through impaired fasting glucose and/or impaired glucose tolerance diagnosis. However, cases exist when oral glucose tolerance test (OGTT) results show an hyperglycemic peak >or =200 mg/dl as a unique alteration. This alteration is defined as impaired hyperglycemic peak (IHP) and should be considered as an additional early indicator of DM2 development. Because IHP is commonly misdetected by the standard OGTT, it is proposed that this misdetection can be solved using a closer sampled OGTT. The objective of this research was to detect IHP on 225 volunteers using a 10 min sampled OGTT during 2 h. Results show the existence of IHP in 25 cases, making it the most frequent and the less detected OGTT alteration. In eight of these cases, IHP could not have been detected using a standard OGTT, because at 30, 60 and 90 min, plasma glucose concentrations were <200 200 mg/dl, however, at 40, 50, 70, and/or 80 min, IHP exists.

The prevention of type 2 diabetes--lifestyle change or pharmacotherapy? A challenge for the 21st century

Diabetes mellitus is occurring in epidemic proportions in many countries. In Australia 7.4% of people over 25 years of age have diabetes (mostly type 2) and comparable or higher prevalences have been reported in the United States and a number of Asian countries. The enormous economic and social cost of this disease makes a compelling case for prevention. Epidemiological studies have shown clearly that type 2 diabetes results from an interaction between a genetic predisposition and lifestyle factors including obesity, sedentary behaviour and both calorie excess and various dietary constituents. The natural history of type 2 diabetes includes a preceding period of impaired glucose tolerance (IGT)/impaired fasting glucose (IFG) which provides an opportunity for targeted intervention within large communities. Lifestyle intervention studies have consistently shown that quite modest changes can reduce the progression from IGT to diabetes by 50-60%. It may, however, not be possible to translate these successful findings to larger cohorts or maintain the lifestyle changes longer term. This has lead to consideration of pharmacotherapy. While small studies with sulphonylureas are inconclusive, benefits have been found for metformin, acarbose and troglitazone. Big intervention studies with ramipril, rosiglitazone, valsartan and nateglinide are underway. Pharmacological intervention raises a whole range of ethical, economic and practical issues not the least of which is the problem of long term therapy of the 'otherwise well'.

Should we consider performing oral glucose tolerance tests more frequently in postmenopausal women for optimal screening of impaired glucose tolerance?

OBJECTIVE

To investigate an optimal screening protocol for impaired glucose tolerance (IGT) and type II or non-insulin-dependent diabetes mellitus (DM) by using fasting plasma glucose (FPG) and oral glucose tolerance test (OGTT) in postmenopausal women.

DESIGN

One hundred consecutive postmenopausal women were screened with FPG determination, and then all underwent an OGTT. Basal serum lipid and insulin levels of these women were also determined. Insulin sensitivity was determined by using the homeostasis model assessment. Receiver operating characteristic analysis was performed to determine the efficacy of these variables in detecting women with IGT and DM, and optimal cutoff values were determined.

RESULTS

FPG with a cutoff value of 98 mg/dL had the best combination of sensitivity (71%) and specificity (76%) for the detection of IGT and DM. Combined FPG and body mass index screening (with the optimal cutoff value of 26.5 kg/m2) improved the sensitivity to 96% but decreased the specificity to 47%. This combined screening protocol detected 94% of the women with IGT and all diabetic women.

CONCLUSIONS

Given that IGT and DM are common among postmenopausal women and DM can be prevented by nonpharmacologic interventions in women with IGT, OGTT may be used more frequently among these women. Our data indicate that for optimal screening of non-insulin-dependent DM and IGT, OGTT should be considered in postmenopausal women, especially when risk factors in addition to age are present. This model may detect most of the women with IGT and almost all diabetic women.

Glucose tolerance and age-associated decline in renal function of hypertensive patients

BACKGROUND

Renal function is thought to decrease with age in the general population, but the determinants of this age-associated evolution are poorly understood. Hypertension and diabetes mellitus, two leading causes of chronic renal failure in the elderly, may accelerate this decline.

PATIENTS AND METHODS

Urinary clearances of [99mTc]diethylene triaminopentaacetic acid (DTPA) (glomerular filtration rate) and [131I]hippuran (effective renal plasma flow) were assessed in 227 never-treated essential hypertensives aged 20-69 years. Based on the oral glucose tolerance test, the study population consisted of 4% patients with previously unknown diabetes mellitus, 24% with impaired glucose tolerance and 72% with normal glucose tolerance.

RESULTS

When the population of 218 non-diabetic subjects was considered, glomerular filtration rate was inversely correlated with age and arterial blood pressure, and positively correlated with effective renal plasma flow, filtration fraction and fasting plasma glucose. In multivariate analysis, age and blood pressure were independent determinants of renal plasma flow, whereas renal plasma flow, age and fasting plasma glucose were independent determinants of glomerular filtration rate. The slope of the regression line relating glomerular filtration rate to age was steeper in patients with impaired glucose tolerance than in those with normal glucose tolerance (-1.52 +/- 0.28 versus -0.65 +/- 0.12, P < 0.01).

CONCLUSIONS

These results suggest that impaired glucose tolerance, which is seldom searched for in patients with essential hypertension, may be an important determinant of the age-associated decline in renal function.

Randomised controlled trial evaluating the effectiveness of behavioural interventions to modify cardiovascular risk factors in men and women with impaired glucose tolerance: outcomes at 6 months

AIMS

To evaluate the efficacy of interventions to promote a healthy diet and physical activity in people with impaired glucose tolerance (IGT).

METHODS

A randomised controlled trial in Newcastle upon Tyne, UK, 1995-98. Participants included 67 adults (38 men; 29 women) aged 24-75 years with IGT. The intervention consisted of regular diet and physical activity counselling based on the stages of change model. Main outcome measures were changes between baseline and 6 months in nutrient intake; physical activity; anthropometric and physiological measurements including serum lipids; glucose tolerance; insulin sensitivity.

RESULTS

The difference in change in total fat consumption was significant between intervention and control groups (difference -21.8 (95% confidence interval (CI) -37.8 to -5.8) g/day, P=0.008). A significantly larger proportion of intervention participants reported taking up vigorous activity than controls (difference 30.1, (95% CI 4.3--52.7)%, P=0.021). The change in body mass index was significantly different between groups (difference -0.95 (95% CI -1.5 to -0.4) kg/m(2), P=0.001). There was no significant difference in change in mean 2-h plasma glucose between groups (difference -0.19 (95% CI -1.1 to 0.71) mmol/l, NS) or in serum cholesterol (difference 0.02 (95% CI -0.26 to 0.31) mmol/l, NS). The difference in change in fasting serum insulin between groups was significant (difference -3.4 (95% CI -5.8 to -1.1) mU/l, P=0.005).

CONCLUSIONS

After 6 months of intensive lifestyle intervention in participants with IGT, there were changes in diet and physical activity, some cardiovascular risk factors and insulin sensitivity, but not glucose tolerance. Further follow-up is in progress to investigate whether these changes are sustained or augmented over 2 years.

The Diabetes Prevention Program: baseline characteristics of the randomized cohort. The Diabetes Prevention Program Research Group

OBJECTIVE

The Diabetes Prevention Program (DPP) is a 27-center randomized clinical trial designed to evaluate the safety and efficacy of interventions that may delay or prevent development of diabetes in people at increased risk for type 2 diabetes.

RESEARCH DESIGN AND METHODS

Eligibility requirements were age > or = 25 years, BMI > or = 24 kg/m2 (> or = 22 kg/m2 for Asian-Americans), and impaired glucose tolerance plus a fasting plasma glucose of 5.3-6.9 mmol/l (or < or = 6.9 mmol for American Indians). Randomization of participants into the DPP over 2.7 years ended in June 1999. Baseline data for the three treatment groups--intensive lifestyle modification, standard care plus metformin, and standard care plus placebo--are presented for the 3,234 participants who have been randomized.

RESULTS

Of all participants, 55% were Caucasian, 20% were African-American, 16% were Hispanic, 5% were American Indian, and 4% were Asian-American. Their average age at entry was 51 +/- 10.7 years (mean +/- SD), and 67.7% were women. Moreover, 16% were < 40 years of age, and 20% were > or = 60 years of age. Of the women, 48% were postmenopausal. Men and women had similar frequencies of history of hypercholesterolemia (37 and 33%, respectively) or hypertension (29 and 26%, respectively). On the basis of fasting lipid determinations, 54% of men and 40% of women fit National Cholesterol Education Program criteria for abnormal lipid profiles. More men than women were current or former cigarette smokers or had a history of coronary heart disease. Furthermore, 66% of men and 71% of women had a first-degree relative with diabetes. Overall, BMI averaged 34.0 +/- 6.7 kg/m2 at baseline with 57% of the men and 73% of women having a BMI > or = 30 kg/m2. Average fasting plasma glucose (6.0 +/- 0.5 mmol/l) and HbA1c (5.9 +/- 0.5%) in men were comparable with values in women (5.9 +/- 0.4 mmol/l and 5.9 +/- 0.5%, respectively).

CONCLUSIONS

The DPP has successfully randomized a large cohort of participants with a wide distribution of age, obesity, and ethnic and racial backgrounds who are at high risk for developing type 2 diabetes. The study will examine the effects of interventions on the development of diabetes.

Diabetes risk score: towards earlier detection of type 2 diabetes in general practice

BACKGROUND

Type 2 diabetes is common, costly and often goes unrecognised for many years. When patients are diagnosed, the majority exhibit associated tissue damage or established cardiovascular risk. Evidence is accumulating that earlier detection and management of diabetes and related metabolic abnormalities may be beneficial. We aimed to develop and evaluate a score based on routinely collected information to identify people at risk of having undetected diabetes.

METHODS

A population-based sample of 1077 people, aged 40 to 64 years, without known diabetes, from a single Cambridgeshire general practice, underwent clinical assessment including an oral glucose tolerance test. In a separate 12-month study, 41 practices in southern England reported clinical details of patients aged 40 to 64 years with newly diagnosed Type 2 diabetes. A notional population was created by random selection and pooling of half of each dataset. Data were entered into a regression model to produce a formula predicting the risk of diabetes. The performance of this risk score in detecting diabetes was tested in an independent, randomly selected, population-based sample.

RESULTS

Age, gender, body mass index, steroid and antihypertensive medication, family and smoking history contributed to the score. In the test population at 72% specificity, the sensitivity of the score was 77% and likelihood ratio 2.76. The area under the receiver-operating characteristic curve was 80%.

CONCLUSIONS

A simple score, using only data that are routinely collected in general practice, can help identify those at risk of diabetes. This score could contribute to efficient earlier detection through case-finding or targeted screening.

Comparison of ADA and WHO screening methods for diabetes mellitus in obese patients. American Diabetes Association

AIMS

To compare the performance of fasting glycaemia (FG) and oral glucose tolerance testing (OGTT) in screening for diabetes mellitus in obese patients.

METHODS

A consecutive series of 528 (445 female, 83 male) obese (body mass index > 30 kg/m2) outpatients, aged 45.2 +/- 14.3 years, was studied with FG and OGTT. The association of categories of glucose tolerance (diabetes and impaired glucose tolerance (IGT)) and fasting glycaemia (diabetes and impaired fasting glucose (IFG)) with hypertension and hyperlipidaemia were also assessed.

RESULTS

Prevalence of diabetes and IGT were 20.1 and 22.9%, respectively. FG (> 7 mmol/l) had a sensitivity of 56.7%. Using FG > 6.1 mmol/l, and OGTT in those above the threshold, the sensitivity for diabetes would have been 89.6%, with a positive predictive value of 59.0%, but 68.8% of cases of IGT would not have been detected. Patients with impaired fasting glucose (FG of 6.1-7.0 mmol/l) showed lower insulin sensitivity and impaired beta cell function, and a weaker association to hypertriglyceridaemia, when compared to IGT.

CONCLUSION

FG > 7.0 mmol/l does not show a sufficient sensitivity for the screening of diabetes in obese patients. FG > 6. mmol/l has a satisfactory sensitivity for diabetes, but not for IGT. IFG has different pathophysiological features than IGT and cannot be assumed to have the same prognostic value of IGT.

The Diabetes Prevention Program. Design and methods for a clinical trial in the prevention of type 2 diabetes

The Diabetes Prevention Program is a randomized clinical trial testing strategies to prevent or delay the development of type 2 diabetes in high-risk individuals with elevated fasting plasma glucose concentrations and impaired glucose tolerance. The 27 clinical centers in the U.S. are recruiting at least 3,000 participants of both sexes, approximately 50% of whom are minority patients and 20% of whom are > or = 65 years old, to be assigned at random to one of three intervention groups: an intensive lifestyle intervention focusing on a healthy diet and exercise and two masked medication treatment groups--metformin or placebo--combined with standard diet and exercise recommendations. Participants are being recruited during a 2 2/3-year period, and all will be followed for an additional 3 1/3 to 5 years after the close of recruitment to a common closing date in 2002. The primary outcome is the development of diabetes, diagnosed by fasting or post-challenge plasma glucose concentrations meeting the 1997 American Diabetes Association criteria. The 3,000 participants will provide 90% power to detect a 33% reduction in an expected diabetes incidence rate of at least 6.5% per year in the placebo group. Secondary outcomes include cardiovascular disease and its risk factors; changes in glycemia, beta-cell function, insulin sensitivity, obesity, diet, physical activity, and health-related quality of life; and occurrence of adverse events. A fourth treatment group--troglitazone combined with standard diet and exercise recommendations--was included initially but discontinued because of the liver toxicity of the drug. This randomized clinical trial will test the possibility of preventing or delaying the onset of type 2 diabetes in individuals at high risk.

Glucose intolerance, cognitive impairment and Alzheimer's disease

The literature on cognitive function and Alzheimer's disease in non-insulin-dependent diabetes, impaired glucose tolerance and hyperinsulinaemia are briefly summarized. Neuropsychological, epidemilogical and endocrine contributions are reviewed, with an emphasis on the insulin hypothesis as a potential pathophysiological mechanism for Alzheimer's disease.

Prevention of type 2 diabetes

Type 2 diabetes is a major cause of morbidity and mortality resulting from its microangiopathic and macroangiopathic complications. Current approaches to its management and to the prevention of diabetic complications are difficult to implement effectively, and there is little evidence to date that these approaches are reducing the impact of this disease. The recognition that type 2 diabetes usually has a prolonged prediabetic phase raises the possibility that the emergence of hyperglycemia and the atherosclerotic complications associated with diabetes may be preventable by the institution of early treatment modalities. Sufficient data suggest that life-style modification or pharmacotherapy directed at improving insulin sensitivity or insulin secretion in subjects with impaired glucose tolerance may reduce progression to diabetes. Two long-term prospective, controlled trials have been initiated to test this hypothesis.

Prevalence of undiagnosed non-insulin-dependent diabetes mellitus and impaired glucose tolerance in a cohort of older persons with hypertension

OBJECTIVE

To determine the prevalence of undiagnosed non-insulin-dependent diabetes mellitus (NIDDM) and impaired glucose tolerance (IGT) in a cohort of older persons with hypertension. To examine the usefulness of screening for NIDDM in this study population.

DESIGN

Cross-sectional study.

SETTING

University of Tennessee, Memphis and the General Clinical Research Center (GCRC).

PATIENTS

Ninety-five participants in the Trial of Nonpharmacologic Interventions in the Elderly (TONE) study who agreed to participate in an ancillary study.

MEASUREMENTS

A standard oral glucose tolerance test (OGTT) with insulin and C-peptide levels was performed before the beginning of the TONE intervention.

RESULTS

In this cohort, 43 participants (45.3%) had normal glucose tolerance (NGT), 41 (43.2%) had IGT, and 11 (11.6%) had undiagnosed NIDDM. The positive predictive value for NIDDM of a fasting glucose > or = 115 mg/dL in our participants was 57%. Hyperinsulinemia occurred in only one participant, a subject in the IGT group.

CONCLUSIONS

Our data demonstrate that undiagnosed NIDDM is common in our cohort of older persons who are being treated for essential hypertension and that impaired glucose tolerance may be more common than in the general population of the same age. Further, our data show that the vast majority of this older, obese, hypertensive cohort did not have fasting hyperinsulinemia. We also infer that a fasting glucose alone has a low positive predictive value for screening of NIDDM in our older cohort. As the prevalence of NIDDM and impaired glucose tolerance in older hypertensive patients in the general population is unknown, we believe that further investigation is needed to characterize the relationship of hypertension, glycemic status, and hyperinsulinemia in the general population.

High glycosylated hemoglobin levels increase the risk of progression to diabetes mellitus in subjects with glucose intolerance

The relationships between HbA1c level and oral glucose tolerance test (OGTT) at the initial visit and the incidence of diabetes after 5 years of follow-up were investigated in 819 subjects participating in a general health examination. The 100 g OGTT was performed. In order to use WHO criteria, the blood glucose levels of 100 g OGTT corresponding to those of 75 g OGTT were adopted according to the recommendations of the Japan Diabetes Society. Subjects other than diabetic type and IGT (impaired glucose tolerance) were divided into a normal group (fasting blood glucose < 100 mg/dl, 1-h blood glucose < 160 mg/dl, a 2-h blood glucose < 120 mg/dl) and a borderline group (the remaining subjects). In IGT, the incidence of diabetes in the low- (< or = 6.3%), intermediate- (6.4-6.7%) and high-HbA1c (> of = 6.8%) groups were 10.4%, 23.1% and 52.5%, respectively (high vs intermediate and low, P < 0.001; intermediate vs low, P < 0.05). In the borderline group, the incidence were 2.8%, 14.3% and 28.6%, respectively (high and intermediate vs low, P < 0.001). The results showed that the combination of HbA1c level and OGTT enables more precise prediction of progression to NIDDM in subjects with glucose intolerance.

Intra-individual variation of glucose, specific insulin and proinsulin concentrations measured by two oral glucose tolerance tests in a general Caucasian population: the Hoorn Study

We studied the intra-individual variation in plasma glucose, specific serum insulin and serum proinsulin concentrations, measured by two 75-g oral glucose tolerance tests in an age, sex, and glucose tolerance stratified random sample from a 50-74-year-old Caucasian population without a history of diabetes mellitus. The intra-individual variation was assessed by the standard deviation of the test-retest differences (SDdif). For subjects with normal (n = 246), impaired glucose tolerance (n = 198), and newly detected diabetes (n = 80) classified at the first test, the following (SDdif/median level of individual average scores) were found: fasting glucose: 0.4/5.4, 0.5/5.9 and 0.7/7.2 mmol/l; 2-h glucose: 1.3/5.6, 1.8/8.5 and 2.3/12.8 mmol/l; fasting insulin: 23/76, 32/89 and 30/116 pmol/l; 2-h insulin: 190/303, 278/553 and 304/626 pmol/l; fasting proinsulin: 4/8, 6/13 and 9/18 pmol/l; 2-h proinsulin: 19/49, 23/84 and 33/90 pmol/l, respectively. In both glucose, proinsulin and insulin concentrations the total intra-individual variation was predominantly determined by biological variation, whereas analytical variation made only a minor contribution. The SDdif can easily be interpreted, as 95% of the random test-retest differences will be less than 2.SDdif, or in terms of percentage, less than (2.SDdif/median level of individual average score) 100. Therefore, for subjects with normal glucose tolerance, 95% of the random test-retest differences will be less than 15% (fasting glucose), 46% (2-h glucose), 61% (fasting insulin), 125% (2-h insulin), 100% (fasting proinsulin) and 78% (2-h proinsulin) of the median value of the individual average scores. No substantial independent association of either age, gender or obesity with the intra-individual variation in glucose, proinsulin, or insulin concentrations was found.