A1C predicts type 2 diabetes and impaired glucose tolerance in a population at risk: the community diabetes prevention project

Impact of triglycerides and waist circumference on insulin resistance and β-cell function in non-diabetic first-degree relatives of type 2 diabetes

BACKGROUND

Although there is abundant evidence indicating the relative contribution of insulin resistance (HOMA-IR) and β-cell dysfunction (HOMA-β) among first-degree relatives (FDRs) of Type 2 DM patients, few studies reported the association between HOMA-IR and HOMA-β with metabolic syndrome. Our objective was to evaluate the impact of metabolic syndrome factors on HOMA-IR, HOMA-β and glycoproteins in non-diabetic FDRs.

METHODS

In this study, 103 Yemeni male subjects aged 25-42 years, with BMI < 25 kg/m² were examined, 39 of whom were normal subjects with no family history of diabetes served as control and 64 subjects were non-diabetic FDRs of Type 2 DM patients.

RESULTS

Both glycoproteins, glycated haemoglobin (HbA1c) and fructosamine as well as insulin, HOMA-IR and HOMA-β were significantly (p = 4.9 × 10^-9; 6.0 × 10^-8; 6.6 × 10^-12; 1.3 × 10^-7; 5.5 × 10^-12, respectively) higher in non-diabetic FDRs as compared to control group. Fasting plasma glucose, though within normal range, were significantly (p = 0.026) higher in non-diabetic FDRs. Linear regression analysis showed that both TG and WC are the main metabolic syndrome factors that significantly increased HOMA-IR (B = 0.334, p = 1.97 × 10^-6; B = 0.024, p = 1.05 × 10^-5), HOMA-β (B = 16.8, p = 6.8 × 10^-5; B = 0.95, p = 0.004), insulin (B = 16.5, p = 1.2 × 10^-6; B = 1.19, p = 8.3 × 10^-6) and HbA1c (B = 0.001, p = 0.034; B = 0.007, p = 0.037).

CONCLUSION

Triglyceride and WC are the important metabolic syndrome factors associated with insulin resistance, basal β-cell function and insulin levels in non-diabetic FDR men of Type 2 DM patients. Moreover, FDRs showed insulin resistance with compensatory β-cell function (hyperinsulinaemia) suggesting that insulin resistance precede the development of pancreatic β-cell dysfunction in individuals at risk of Type 2 DM.

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.

The application of visceral adiposity index in identifying type 2 diabetes risks based on a prospective cohort in China

Background

Visceral adiposity index (VAI), a novel sex-specific index for visceral fat measurement, has been proposed recently. We evaluate the efficacy of VAI in identifying diabetes risk in Chinese people, and compare the predictive ability between VAI and other body fatness indices, i.e., waist circumference (WC), body mass index (BMI) and waist- to- height ratio (WHtR).

Methods

Participants (n = 3,461) were recruited from an ongoing cohort study in Jiangsu Province, China. Hazard ratio (HR) and corresponding 95% confidence interval (CI) between diabetes risk and different body fatness indices were evaluated by Cox proportional hazard regression model. Receiver operating characteristic (ROC) curve and area under curve (AUC) were applied to compare the ability of identifying diabetes risk between VAI, WC, WHtR and BMI.

Results

A total number of 160 new diabetic cases occurred during the follow-up, with an incidence of 4.6%. Significant positive associations were observed for VAI with blood pressure, fasting plasma glucose, triglyceride, WC, BMI and WHtR. Moreover, increased VAI was observed to be associated with higher diabetes risk with a positive dose–response trend (p for trend < 0.001). As compared to individuals with the lowest VAI, those who had the highest VAI were at 2.55-fold risk of diabetes (95% CI: 1.58-4.11). The largest AUC was observed for VAI, following by WC, WHtR and BMI.

Conclusions

VAI is positively associated with the risk of diabetes. Compared to other indices for body fatness measurements, VAI is a better and convenience surrogate marker for visceral adipose measurement and could be used in identifying the risk of diabetes in large-scale epidemiologic studies.

Three-year's changes in glucose tolerance status in the Bellville South cohort: rates and phenotypes associated with progression

AIMS

To determine the phenotypes associated with progression to type 2 diabetes or worsening in glucose tolerance during a 3-year follow-up of a community-based cohort in Cape Town, South Africa.

METHODS

A total of 198 eligible subjects (72.3% women) aged 55.2 years, from the Bellville-South community were followed-up between 2008 and 2011. Baseline and follow-up data collections included glucose tolerance status, anthropometric, blood pressure, lipids, insulin, γ-glutamyltransferase, cotinine, creatinine and HbA1c. Progression in glucose tolerance status at 3-year was the composite of new-onset diabetes and any worsening in glucose tolerance status.

RESULTS

The cumulative incidence of progression in glucose tolerance status was: 16.2% (32 participants including 11 with new-onset diabetes), and increased in a stepwise fashion with the number of components of metabolic syndrome (MetS). In age and sex-adjusted logistic regression analyses, MetS [odd ratio: 3.08 (95% CI: 1.34-7.10)], HbA1c [5.26 (1.94-14.24)], HDL-cholesterol [0.05 (0.01-0.33)], γ-glutamyltransferase [1.99 (1.07-3.67)], triglycerides [1.71 (1.13-2.58)] and total/HDL-cholesterol [1.45 (1.08-1.93)] were significant predictors of progression, while borderline effects were observed for baseline glucose and diastolic blood pressure. Markers of adiposity were mostly stable or improved among non-progressors during follow-up, but deteriorated significantly among progressors, resulting in significant statistical interactions.

CONCLUSIONS

High rates of deterioration of glucose status over time were found in our population, with nearly one-fifth of them acquiring a glucose tolerance worse status within a very short follow-up. Our study extends to this setting the well-known utility of phenotypes of MetS single or in combination, in predicting worsening in glucose tolerance status.

Impact of hyperglycemia on morbidity and mortality, length of hospitalization and rates of re-hospitalization in a general hospital setting in Brazil

BACKGROUND

Hyperglycemia in hospitalized patients is known to be related to a higher incidence of clinical and surgical complications and poorer outcomes. Adequate glycemic control and earlier diagnosis of type 2 diabetes during hospitalization are cost-effective measures.

METHODS

This prospective cohort study was designed to determine the impact of hyperglycemia on morbidity and mortality in a general hospital setting during a 3-month period by reviewing patients' records. The primary purposes of this trial were to verify that hyperglycemia was diagnosed properly and sufficiently early and that it was managed during the hospital stay; we also aimed to evaluate the relationship between in-hospital hyperglycemia control and outcomes such as complications during the hospital stay, extent of hospitalization, frequency of re-hospitalization, death rates and number of days in the ICU (Intensive Care Unit) after admission. Statistical analyses utilized the Kruskall-Wallis complemented by the "a posteriori" d.m.s. test, Spearman correlation and Chi-squared test, with a level of significance of 5% (p < 0.05).

RESULTS

We reviewed 779 patient records that fulfilled inclusion criteria. The patients were divided into 5 groups: group (1) diabetic with normal glycemic levels according to American Diabetes Association criteria for in-hospital patients (n = 123); group (2) diabetics with hyperglycemia (n = 76); group (3) non-diabetics with hyperglycemia (n = 225); group (4)diabetics and non-diabetics with persistent hyperglycemia during 3 consecutive days (n = 57) and group (5) those with normal glucose control (n = 298). Compared to patients in groups 1 and 5, patients in groups 2, 3 and 4 had significantly higher mortality rates (17.7% vs. 2.8%) and Intensive Care Unit admissions with complications (23.3% vs. 4.5%). Patients in group 4 had the longest hospitalizations (mean 15.5 days), and group 5 had the lowest re-hospitalization rate (mean of 1.28 hospitalizations). Only 184 (51.4%) hyperglycemic patients had received treatment. An insulin "sliding-scale" alone was the most frequent treatment used, and there was a wide variation in glucose target medical prescriptions. Intra Venous insulin infusion was used in 3.8% of patients in the ICU. Glycohemoglobin(A1C) was measured in 11 patients(2.2%).

CONCLUSIONS

Hospital hyperglycemia was correlated with, among other parameters, morbidity/mortality, length of hospitalization and number of re-hospitalizations. Most patients did not have their glycemic levels measured at the hospital; despite the high number of hyperglycemic patients not diagnosed as diabetics, A1C was not frequently measured. Even when patients are assessed for hyperglycemia, they were not treated properly.