Elevated A1C is associated with impaired early-phase insulin secretion rather than insulin resistance in Koreans at high risk for developing diabetes

Family History of Diabetes and the Effectiveness of Lifestyle Intervention on Insulin Secretion and Insulin Resistance in Chinese Individuals with Metabolic Syndrome

AIMS

The current study aims to explore if a family history of diabetes can influence the efficiency of lifestyle intervention on insulin secretion and study the insulin resistance in Chinese men and women with metabolic syndrome in a cohort with a 2-year follow-up.

METHODS

151 individuals (90 individuals did not have a family history of diabetes (DMFH (-)) and 61 with a family history of diabetes (DMFH (+)) with metabolic syndrome participated in the lifestyle intervention program at baseline and finished with 1-year follow-up. 124 individuals have two-year follow-up data. A family history of diabetes was ascertained by self-report. Lifestyle interventions were individual sessions on lifestyle changes.

RESULTS

During the 1-year follow-up, Ln Insulinogenic index (Δ_{baseline-1year} = 0.29 ± 0.65, P = 0.001) and 30-min glucose (Δ_{baseline-1year} = -0.41 ± 1.71, P = 0.024) changed significantly in the DMFH(-) group; in the DMFH(+) group, Ln ISIm (Δ_{baseline-1year} = -0.22 ± 0.60, P = 0.022) and 30-min glucose (Δ_{baseline-1year} = 0.53 ± 1.89, P = 0.032) changed significantly, and there was no significant change of other parameters. The change of 30 min glucose during a 1-year intervention has shown a significant difference between the two groups (P = 0.002). During the 2 years intervention, Ln Insulinogenic index changed significantly in the DMFH(-) group (Δ_{baseline-1year} = 0.33 ± 0.66, P < 0.001 and Δ_{baseline-2year} = 0.43 ± 1.17, P = 0.034). Fasting insulin (Δ_{baseline-2year} = 2.95 ± 8.69, P = 0.034), 2 h insulin (Δ_{baseline-2year} = 23.75 ± 44.89, P = 0.002), Ln HOMA-B (Δ_{baseline-2year} = 0.43 ± 1.02, P = 0.009), Ln HOMA-IR (Δ_{baseline-2year} = 0.53 ± 1.04, P = 0.002), Ln ISIm (Δ_{baseline-2year} = 0.52 ± 0.95, P = 0.004), and Ln Insulinogenic index (Δ_{baseline-2year} = 0.66 ± 1.18, P = 0.047) changed significantly after 2 years of intervention, compared to the baseline in the DMFH(+) group. The change of Ln ISIm (P = 0.023), fasting (P = 0.030), and 2 h insulin (P = 0.007) during the 2-year intervention has shown a significant difference between the two groups. Family history of diabetes was related with a 0.500 unit increase in 2-year ISIm (P = 0.020) modified by lifestyle intervention adjusted for age, baseline BMI, sex, and baseline waist circumference and a 0.476 unit increase in 2-year ISIm (P = 0.027) with extra adjustment for weight change.

CONCLUSIONS

Patients with a family history of diabetes benefit more from lifestyle intervention in regard to insulin resistance than those without a family history of diabetes adjusting for age, baseline BMI, sex, baseline waist circumference, and weight change.

The ratio of fasting plasma glucose to hemoglobin A1c as a predictor of all-cause mortality in individuals with normal glucose levels: The Jichi Medical School cohort study

OBJECTIVES

The fasting plasma glucose/hemoglobin A1c ratio is considered a marker associated with glucose metabolism disorders, including fasting hyperglycemia. However, it remains unclear whether this ratio can be used for the prevention of deaths in individuals with normal fasting plasma glucose levels. This study aimed to see the predictive value of the fasting plasma glucose/hemoglobin A1c ratio for all-cause mortality in a general population with normal fasting plasma glucose levels.

METHODS

The study investigated prospectively a cohort of 1087 multi-regional, community-dwelling Japanese participants (women, 69.2%) for a follow-up period of 11.3 years. We included individuals with fasting plasma glucose levels <6.11 mmol/L and excluded those meeting the diabetes criteria. All-cause mortality was the primary outcome and hazard ratios were calculated using the Cox proportional hazard model after dividing the fasting plasma glucose/hemoglobin A1c ratios into tertiles.

RESULTS

There were 54 deaths (25 women) during the follow-up period. The high tertile group had a significantly higher hazard ratio for all-cause mortality than the low tertile group in women (multivariate-adjusted hazard ratio = 4.45; 95% confidence interval = 1.26-15.72), but not clearly in men.

CONCLUSION

The data of the population-based cohort study suggest that a high fasting plasma glucose/hemoglobin A1c ratio can predict all-cause mortality in women with normal fasting plasma glucose levels.

Different Analysis of β-Cell Dysfunction as Fasting Glucose Progresses in Obese and Nonobese Newly Diagnosed Type 2 Diabetic Patients

AIMS/INTRODUCTION

This study is aimed at (1) investigating the change of β-cell dysfunction as baseline fasting glucose progresses in newly diagnosed patients with T2DM and (2) finding whether body mass index (BMI) has different degrees of impact on insulin secretion as baseline fasting glucose progresses.

MATERIALS AND METHODS

661 patients with newly diagnosed T2DM were enrolled in the present study. A 75 g oral glucose tolerance test was used to calculate HOMA-β, HOMA-IR, early-phase insulin secretion index (EISI, calculated as ΔI₃₀/ΔG₃₀), and area under the insulin releasing curve (AUC_I0-180). Patients were divided into low, medium, and high FBG groups. Each group was further divided into lean, overweight, and obese subgroups according to BMI.

RESULTS

A decrease of EISI and HOMA-β and an increase of HOMA-IR were shown among different FBG groups significantly. In the medium FBG group, AUC_I0-180, EISI, HOMA-β, and HOMA-IR in obese patients were higher than those in lean and overweight patients. In the low and high FBG groups, AUC_I0-180, HOMA-β, and HOMA-IR in obese patients were higher than those in other subgroups. BMI was positively associated with high EISI in the medium FBG group but failed to yield a significant association with EISI in the low and high FBG groups.

CONCLUSIONS

During the progression of baseline FBG, β-cell dysfunction and insulin resistance worsened. As FBG increased, increased BMI had a positive influence on β-cell dysfunction in all FBG groups. The independent factors that correlated to EISI differed with the increasing of baseline FBG.

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.

Impaired β-cell function and decreased insulin sensitivity in subjects with normal oral glucose tolerance but isolated high glycosylated hemoglobin

The pathophysiology is distinct in various state of glucose metabolism abnormalities. As the defect of individuals with normal oral glucose tolerance (NGT) but isolated high glycosylated hemoglobin (HbA1c), i.e. iHH, was ambiguous, we aimed to investigate the insulin sensitivity and β-cell function of iHH. According to the ADA criteria of HbA1c cut-off point (5.7%), 3,517 subjects with NGT screened from a total of 7,855 middle-aged and elderly Chinese without known diabetes were divided into two groups, 1,877 subjects with HbA1c < 5.7% and 1,640 with HbA1c ≥ 5.7% (i.e. iHH). A variety of indexes from blood glucose and insulin levels of oral glucose tolerance were calculated to evaluate insulin sensitivity and β-cell function. Compared with subjects with HbA1c < 5.7%, individuals with iHH had increased homeostasis model assessment of insulin resistance (HOMA-IR), early-phase and total insulin release indexes (insulin release index 30 min and 120 min, i.e. INRS30 and INSR120), and decreased Matsuda insulin sensitivity index (Matsuda ISI) and early-phase disposition index (DI30). After adjustment for confounding factors, the significant difference of HOMA-IR and INSR30 between the two groups vanished, however, Matsuda ISI and DI30 remained significantly lower and INSR120 was still higher in iHH group compared with HbA1c < 5.7%. In conculsion, subjects with NGT may not be perfectly healthy in glycometabolism, those with iHH have impaired early-phase β-cell function and decreased insulin sensitivity.

Factors Affecting Hemoglobin A1C in the Diagnosis of Diabetes and Prediabetes in Youth

We sought to examine the correlation between variables and A1C levels to determine if prediction modeling could be used in the screening and diagnosis of diabetes and prediabetes in youth. We also sought to test relationships between A1C levels to insulin sensitivity indices and β-cell function indices.

DESIGN AND METHODS

We performed a retrospective review of 904 medical records from youth deemed at-risk for the disease. We performed Pearson correlation, multiple regression, and simple regression testing to determine the relationship between variables and A1C levels. In addition, we performed Pearson correlation testing on insulin sensitivity indices and β-cell function indices to determine the strength of correlation to A1C levels.

RESULTS

Statistical analysis did not show a strong relationship between the variables tested and the A1C. When racial and ethnic groups were tested together, the results from African American participants resulted in bias estimates, and as a result, a statistical model for the entire sample could not be performed. Results indicate that A1C is correlated with all β-cell function proxy measurements and correlated to the corrected insulin level at 30minutes, but not the fasting insulin or insulinogenic index.

DISCUSSION

The results from this study underline the multi-dimensional causes of diabetes and prediabetes and further stress the difficulties in predicting the diseases. The causes of diabetes and prediabetes are multifaceted, often individualized, and often difficult to ascertain.

PRACTICE IMPLICATIONS

Clinicians should continue to examine a variety of variables prior to determining the need for diabetes diagnostic testing.

Relationship between neutrophil-lymphocyte ratio and insulin resistance in newly diagnosed type 2 diabetes mellitus patients

BACKGROUND

Insulin resistance (IR) plays a vital role in the pathogenesis of Type 2 Diabetes Mellitus (T2DM). The mechanism of IR may be associated with inflammation, whereas the neutrophil-lymphocyte ratio (NLR) is a new indicator of subclinical inflammation. Scholars have rarely investigated the relationship between IR and NLR. This study aims to evaluate the relationship between IR and NLR, and determine whether or not NLR is a reliable marker for IR.

METHODS

The sample consists of a total of 413 patients with T2DM, 310 of whom have a HOMA-IR value of > 2.0. The control group consists of 130 age and BMI matched healthy subjects.

RESULTS

The NLR values of the diabetic patients were significantly higher than those of the healthy control (P < 0.001), and the NLR values of the patients with a HOMA-IR value of > 2.0 are notably greater than those of the patients with a HOMA-IR value of ≤ 2.0 (P < 0.001). Pearson correlation analysis showed a significant positive correlation of NLR with HOMA-IR (r = 0.285) (P < 0.001). Logistic regression analysis showed that the risk predictors of IR include NLR, TG and HbA1c. NLR (P < 0.001, EXP(B) = 7.231, 95% CI = 4.277-12.223) levels correlated positively with IR. The IR odds ratio increased by a factor of 7.231 (95% CI, 4.277-12.223) for every one unit increase in NLR.

CONCLUSIONS

Increased NLR was significantly associated with IR, and high NLR values may be a reliable predictive marker of IR.

Examination of the fasting and 2-h plasma glucose in the light of impairment in beta-cell function: what does the epidemiological data tell us?

We re-assess the fasting plasma glucose (FPG) and 2-h post-load glucose (2HPG) in the diagnosis of both prediabetes and type 2 diabetes mellitus by developing a gold standard based on beta-cell function. The gold standard was developed in a cohort of 2,152 adult subjects without severe renal or liver dysfunction that also had a 2-h oral glucose tolerance test (OGTT) during the Third National Health and Nutrition Examination Survey. Beta-cell function was computed based on a composite of insulin secretion (determined based on the insulin and glucose responses to the OGTT) and the homeostasis model insulin resistance index. The X-tile program was used to generate the most appropriate categories of minor, moderate and severe impairment of beta-cell function based on the best discrimination of ln(insulin secretion). Subjects with a moderate or severe impairment in beta-cell function were used to define prediabetes and diabetes, respectively, and was the standard against which the FPG and 2HPG were evaluated. It is shown that the current definitions of diabetes by the FPG and 2HPG mirror those derived using impairment of beta-cell function as the gold standard. It is also shown that lowering the cutoff for the FPG does little to improve its use in the screening for prediabetes. A major finding is that the current 2HPG cutoff is inadequate and thus in need of revision to >6.7 mmol/L (>120 mg/dL) from 7.8 mmol/L (140 mg/dL) for the lower cutoff. The use of a model of beta-cell function and impairment of insulin secretion has thus put the utility of the FPG and 2HPG into perspective: We recommend that performing an OGTT be considered pivotal for accurate identification of subjects with impaired beta-cell function (and thus prediabetes) and a revision of the OGTT lower cutoff be considered based on the results of this study.

High-normal 2 h glucose is associated with defects of insulin secretion and predispose to diabetes in Chinese adults

The purpose of the study was to determine whether impaired beta-cell function exists in Chinese individuals within the normal range of glucose tolerance (NGT), and these individuals are predisposed to diabetes later in life. The cross-sectional study included 843 NGT subjects and 562 isolated impaired glucose tolerance (IGT) patients and the longitudinal study included 1,724 NGT subjects. Insulin secretion was assessed using indices derived from oral glucose tolerance test and adjusted by insulin resistance. NGT subjects were sub-divided into two groups: NGT-l (2hPG<125 mg/dl) and NGT-h (2hPG 125-140 mg/dl). Normal weight subjects were individuals with BMI<25 kg/m2, and overweight were with BMI≥25 kg/m2. In normal weight subjects, the first- and second-phase insulin secretion indices were significantly higher in NGT-h and NGT-l subjects compared with IGT subjects. However, in overweight subjects, first-phase insulin secretion index in NGT-h subjects was significantly lower than that in NGT-l subjects, but similar to that in IGT patients. The second-phase insulin secretion was comparable between NGT-h and NGT-l subjects. After an average follow-up of 43.80±11.25 months, totally 25 (1.5%) NGT subjects at baseline developed diabetes. The incidence rate of diabetes was higher in NGT-h overweight subjects (9.2%) than in NGT-l overweight subjects (1.5%) with a risk ratio (RR) reaching 6.655 [95% confidence interval (CI) 2.347-18.867]. This risk remained after adjustment for sex, age, BMI, systolic pressure, and diastolic pressure (RR 8.315, 95% CI 2.649-26.108). It is concluded that overweight NGT adults with high-normal 2hPG (≥125 mg/dl) had a defect in first-phase insulin secretion and were with the increasing risk for developing new diabetes.

The Early Diabetes Intervention Program--is early actually late?

This Commentary briefly reviews the background of prediabetes including its definition and pathophysiology and describes as well the natural course of glycemic deterioration as it follows a continuum. Research efforts in identifying glucose and other biomarkers for the early detection of high-risk individuals are summarized.

Impact of incretin on early-phase insulin secretion and glucose excursion

This study investigated the impact of incretin on early-phase insulin secretion and glucose excursion. The normal glucose tolerance (NGT), impaired glucose tolerance (IGT), and type 2 diabetes mellitus (T2DM) groups included 16, 8, and 19 subjects, respectively. Subjects underwent continuous glucose monitoring for 3 days, followed by an oral glucose tolerance test. Plasma glucose, insulin, glucagon, total glucose-dependent insulinotropic polypeptide (GIP), and glucagon-like peptide-l (GLP-1) levels were measured at 30-min increments for 2 h after glucose intake. Differences with P < 0.05 were considered statistically significant. The area under the curve (AUC) of total GIP (120-min GIP-AUC) of the T2DM group was significantly lower than those of the NGT and IGT groups. The 120-min GLP-1-AUC of the NGT group was significantly larger than those of the T2DM and IGT groups. The early-phase insulin secretion index (ΔI30/ΔG30) of the T2DM group was significantly lower than those of the NGT and IGT groups. Mean amplitudes of glycemic excursions (MAGEs) went in the order of NGT < IGT < T2DM (P < 0.01, IGT vs. NGT; P < 0.001, T2DM vs. IGT). The 120-min GIP-AUC was negatively correlated with MAGE (r = -0.464), but uncorrelated with ΔI30/ΔG30. The 120-min GLP-1-AUC was positively correlated with ΔI30/ΔG30 (r = 0.580), but negatively correlated with MAGE (r = -0.606). Incretin may ameliorate glucose excursions, and GLP-1 may exert them by promoting early-phase insulin secretion. No correlation was observed between GIP secretion and early-phase insulin secretion.