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

Constructing a metabolic integral score model for the quantification of metabolic dysfunction and tendency

BACKGROUND AND AIMS

The binary nature of metabolic syndrome (MetS) cannot quantitatively describe the severity of metabolic abnormalities. We aim to establish a metabolic integral score (MIS) model to quantify the severity and polarity of metabolic disorders and their relationship with insulin sensitivity and secretion.

METHODS AND RESULTS

We performed factor analysis on 9950 participants from a cross-sectional study conducted in China. The MIS model was established using 10 variables including body mass index (BMI), waist circumference, hip circumference, glycosylated hemoglobin (HbA1c), fasting and 2-h plasma glucose (FPG, 2h-PG), systolic blood pressure (SBP), diastolic blood pressure (DBP), high-density lipoprotein (HDL) and triglyceride (TG) levels. Four common factors were identified as "glucose factor," "obesity factor," "blood pressure factor," and "lipid factor," respectively, in MIS model (KMO = 0.755, P < 0.001). MIS = 0.433 × Factor 1 + 0.267 × Factor 2 + 0.172 × Factor 3 + 0.128 × Factor 4. Insulin sensitivity and β-cell function decreased with the increase of MIS (P < 0.001). We classified four metabolic tendencies according to factor quartiles. Individuals in Tendency 1 (severe hyperglycemia) had the worst β-cell function. Tendency 3 (severe hypertension) had the best insulin sensitivity. Tendency 4 (severe dyslipidemia) had preferable β-cell function (P < 0.05).

CONCLUSIONS

Our MIS model provides a quantitative scoring system to assess various patterns of metabolic abnormality that indicate different underlying pathophysiology.

Profiles of Glucose Metabolism in Different Prediabetes Phenotypes, Classified by Fasting Glycemia, 2-Hour OGTT, Glycated Hemoglobin, and 1-Hour OGTT: An IMI DIRECT Study

Differences in glucose metabolism among categories of prediabetes have not been systematically investigated. In this longitudinal study, participants (N = 2,111) underwent a 2-h 75-g oral glucose tolerance test (OGTT) at baseline and 48 months. HbA_1c was also measured. We classified participants as having isolated prediabetes defect (impaired fasting glucose [IFG], impaired glucose tolerance [IGT], or HbA_1c indicative of prediabetes [IA1c]), two defects (IFG+IGT, IFG+IA1c, or IGT+IA1c), or all defects (IFG+IGT+IA1c). β-Cell function (BCF) and insulin sensitivity were assessed from OGTT. At baseline, in pooling of participants with isolated defects, they showed impairment in both BCF and insulin sensitivity compared with healthy control subjects. Pooled groups with two or three defects showed progressive further deterioration. Among groups with isolated defect, those with IGT showed lower insulin sensitivity, insulin secretion at reference glucose (ISR_r), and insulin secretion potentiation (P < 0.002). Conversely, those with IA1c showed higher insulin sensitivity and ISR_r (P < 0.0001). Among groups with two defects, we similarly found differences in both BCF and insulin sensitivity. At 48 months, we found higher type 2 diabetes incidence for progressively increasing number of prediabetes defects (odds ratio >2, P < 0.008). In conclusion, the prediabetes groups showed differences in type/degree of glucometabolic impairment. Compared with the pooled group with isolated defects, those with double or triple defect showed progressive differences in diabetes incidence.

Increased risks of different grades of non-alcoholic fatty liver disease in prediabetic subjects with impaired fasting glucose and glucose tolerance, including the isolated glycosylated hemoglobin levels of 5.7-6.4% in a Chinese population

AIMS/INTRODUCTION

Contrary to the results of the majority of studies on diabetes, there are some conflicting results regarding the relationship between non-alcoholic fatty liver disease (NAFLD) and prediabetes. No study has investigated the relationship between isolated glycated hemoglobin (HbA1c) in the range of 5.7-6.4% (HbA1c 5.7-6.4%) and NAFLD. Our aim was to investigate the effect of different glycemic statuses on NAFLD concomitantly categorized by fasting plasma glucose, 2-h plasma glucose and HbA1c levels.

MATERIALS AND METHODS

NAFLD was classified into three groups by ultrasonographic examination results: normal, mild and moderate-to-severe. Glycemic status was divided into five groups: normoglycemia, isolated HbA1c 5.7-6.4%, impaired fasting glucose without impaired glucose tolerance (IGT), IGT and newly diagnosed diabetes. For multivariable logistic regression analyses, the outcome variable was the classified three grades of fatty changes in the liver after adjusting for other potential risk covariables.

RESULTS

In this cross-sectional research, a total of 8,571 eligible individuals were enrolled and divided into three groups: 5,499 without fatty liver, 2,113 with mild NAFLD and 959 with moderate-to-severe NAFLD. Multivariable logistic regression analysis showed that IGT, impaired fasting glucose without IGT and isolated HbA1c 5.7-6.4% were associated with a higher risk of NAFLD in addition to newly diagnosed diabetes. Other positively predictive variables were male sex, obesity, overweight, central obesity, increased triglyceride and C-reactive protein >1 mg/L. Negatively associated factors were elevated high-density lipoprotein cholesterol levels.

CONCLUSIONS

Besides diabetes, the increased risks of different grades of NAFLD were found for prediabetic individuals categorized by impaired fasting glucose without IGT, IGT and isolated HbA1c 5.7-6.4%.