The 1-Hour Plasma Glucose: Common Link Across the Glycemic Spectrum

International Diabetes Federation Position Statement on the 1-hour post-load plasma glucose for the diagnosis of intermediate hyperglycaemia and type 2 diabetes

Many individuals with intermediate hyperglycaemia (IH), including impaired fasting glycaemia (IFG) and impaired glucose tolerance (IGT), as presently defined, will progress to type 2 diabetes (T2D). There is confirmatory evidence that T2D can be prevented by lifestyle modification and/or medications, in people with IGT diagnosed by 2-h plasma glucose (PG) during a 75-gram oral glucose tolerance test (OGTT). Over the last 40 years, a wealth of epidemiological data has confirmed the superior value of 1-h plasma glucose (PG) over fasting PG (FPG), glycated haemoglobin (HbA1c) and 2-h PG in populations of different ethnicity, sex and age in predicting diabetes and associated complications including death. Given the relentlessly rising prevalence of diabetes, a more sensitive, practical method is needed to detect people with IH and T2D for early prevention or treatment in the often lengthy trajectory to T2D and its complications. The International Diabetes Federation (IDF) Position Statement reviews findings that the 1-h post-load PG ≥ 155 mg/dL (8.6 mmol/L) in people with normal glucose tolerance (NGT) during an OGTT is highly predictive for detecting progression to T2D, micro- and macrovascular complications, obstructive sleep apnoea, cystic fibrosis-related diabetes mellitus, metabolic dysfunction-associated steatotic liver disease, and mortality in individuals with risk factors. The 1-h PG of 209 mg/dL (11.6 mmol/L) is also diagnostic of T2D. Importantly, the 1-h PG cut points for diagnosing IH and T2D can be detected earlier than the recommended 2-h PG thresholds. Taken together, the 1-h PG provides an opportunity to avoid misclassification of glycaemic status if FPG or HbA1c alone are used. The 1-h PG also allows early detection of high-risk people for intervention to prevent progression to T2D which will benefit the sizeable and growing population of individuals at increased risk of T2D. Using a 1-h OGTT, subsequent to screening with a non-laboratory diabetes risk tool, and intervening early will favourably impact the global diabetes epidemic. Health services should consider developing a policy for screening for IH based on local human and technical resources. People with a 1-h PG ≥ 155 mg/dL (8.6 mmol/L) are considered to have IH and should be prescribed lifestyle intervention and referred to a diabetes prevention program. People with a 1-h PG ≥ 209 mg/dL (11.6 mmol/L) are considered to have T2D and should have a repeat test to confirm the diagnosis of T2D and then referred for further evaluation and treatment. The substantive data presented in the Position Statement provides strong evidence for redefining current diagnostic criteria for IH and T2D by adding the 1-h PG.

Prevalence of prediabetes in Mexico: a retrospective analysis of nationally representative surveys spanning 2016-2022

Background

Characterizing prediabetes phenotypes may be useful in guiding diabetes prevention efforts; however, heterogeneous criteria to define prediabetes have led to inconsistent prevalence estimates, particularly in low- and middle-income countries. Here, we estimated trends in prediabetes prevalence in Mexico across different prediabetes definitions and their association with prevalent cardiometabolic conditions.

Methods

We conducted a serial cross-sectional analysis of National Health and Nutrition Surveys in Mexico (2016-2022), totalling 22 081 Mexican adults. After excluding individuals with diagnosed or undiagnosed diabetes, we defined prediabetes using ADA (impaired fasting glucose [IFG] 100-125 mg/dL and/or HbA1c 5.7-6.4%), WHO (IFG 110-125 mg/dL), and IEC criteria (HbA1c 6.0-6.4%). Prevalence trends of prediabetes over time were evaluated using weighted Poisson regression and its association with prevalent cardiometabolic conditions with weighted logistic regression.

Findings

The prevalence of prediabetes (either IFG or high HbA1c [ADA]) in Mexico was 20.9% in 2022. Despite an overall downward trend in prediabetes (RR 0.973, 95% CI 0.957-0.988), this was primarily driven by decreases in prediabetes by ADA-IFG (RR 0.898, 95% CI 0.880-0.917) and WHO-IFG criteria (RR 0.919, 95% CI 0.886-0.953), while prediabetes by ADA-HbA1c (RR 1.055, 95% CI 1.033-1.077) and IEC-HbA1C criteria (RR 1.085, 95% CI 1.045-1.126) increased over time. Prediabetes prevalence increased over time in adults >40 years, with central obesity, self-identified as indigenous or living in urban areas. For all definitions, prediabetes was associated with an increased risk of cardiometabolic conditions.

Interpretation

Prediabetes rates in Mexico from 2016 to 2022 varied based on defining criteria but consistently increased for HbA1c-based definitions and high-risk subgroups.

Funding

This research was supported by Instituto Nacional de Geriatría in Mexico. JAS was supported by NIH/NIDDK Grant# K23DK135798.

Predisposition to Type 2 Diabetes in Aspects of the Glycemic Curve and Glycated Hemoglobin in Healthy, Young Adults: A Cross-sectional Study

OBJECTIVES

Our aim in this study was to identify predictors for diabetes among the characteristics of the glycemic curve and glycated hemoglobin (A1C) in healthy, young adults.

METHODS

We used a cross-sectional study to establish predictors for diabetes based on earlier studies and evaluated occurrence of the condition in 81 healthy, young adult subjects. These volunteers underwent analysis of fasting plasma glucose, oral glucose tolerance test plasma glucose, A1C, and inflammatory markers (leukocytes, monocytes, and C-reactive protein). The nonparametric Mann-Whitney U test, Fisher's exact test, chi-square test, Kruskal-Wallis test, and multiple-comparisons test were used to analyze the data.

RESULTS

We studied 2 age groups, homogeneous in terms of family history of diabetes: one group ranged in age from ≥18 to <28 years (median 20 years; body mass index [BMI] 24 kg/m2) and the other group ranged in age from ≥28 to <45 years (median 35 years; BMI 24 kg/m2). The older group had a higher incidence of predictors (p=0.0005) and was associated with the predictors 30-minute blood glucose ≥164 mg/dL (p=0.0190), 60-minute blood glucose ≥125 mg/dL (p=0.0346), and A1C ≥5.5% (p=0.0162), with a monophasic glycemic curve (p=0.007). The younger group was associated with the 2-hour plasma glucose predictor ≥140 mg/dL (p=0.014). All subjects had fasting glucose in the normal range.

CONCLUSIONS

Healthy, young adults may already have predictors of diabetes, identified mainly by aspects of the glycemic curve and A1C, but at more modest levels than those with prediabetes.

One-Hour Post-Load Plasma Glucose and Altered Glucometabolic Profile in Youths with Overweight or Obesity

In youths, two cut-offs (133 and 155 mg/dL) have been proposed to identify high glucose levels at the 1 h (G60) mark during an oral glucose tolerance test (OGTT). We evaluated which cut-off was more closely associated with isolated impaired glucose tolerance (IGT) and cardiometabolic risk (CMR) in 1199 youth with overweight/obesity (OW/OB) and normal fasting glucose and/or HbA1c. The disposition index (DI) was available in 724 youths. The sample was divided by two cut-offs of G60: <133 mg/dL (n = 853) and ≥133 mg/dL (n = 346), or G60 < 155 mg/dL (n = 1050) and ≥155 mg/dL (n = 149). Independent of the cut-off, youths with high levels of G60 showed higher levels of G120, insulin resistance (IR), triglycerides to HDL ratio (TG/HDL), alanine aminotransferase (ALT), and lower insulin sensitivity (IS) and DI than youths with lower levels of G60. The percentage of youths showing IGT, IR, low IS, high TG/HDL ratio, high ALT, and low DI was 50% higher in the G60 ≥ 133 mg/dL group than in the G60 ≥ 155 mg/dL one. In youths with OW/OB and IGT, a cut-off of G60 ≥ 133 mg/dL is more useful than G60 ≥ 155 mg/dL to identify those at high risk of IGT and altered CMR profile.

One-hour plasma glucose level after a 75 g oral glucose load and its relationship to gastric emptying in survivors of critical illness and stress hyperglycaemia

Objective: A 1-hour plasma glucose level ≥ 8.6 mmol/L in a 75 g oral glucose tolerance test has been strongly associated with increased morbidity and mortality in outpatients without diabetes. Our primary aim was to evaluate the 1-hour plasma glucose level in a 75 g glucose tolerance test in survivors of critical illness with stress hyperglycaemia at 3 months after intensive care unit (ICU) discharge, with the secondary aims to evaluate the 2-hour plasma glucose level, glycated haemoglobin (HbA1c), and gastric emptying. Design:Post hoc analysis of a single-centre, prospective cohort study. Setting: Single-centre, tertiary referral, mixed medical-surgical ICU. Participants: Consecutively admitted patients aged ≥ 18 years who developed stress hyperglycaemia and survived to hospital discharge were eligible. Interventions: Participants returned at 3 months after ICU discharge and underwent a 75 g oral glucose tolerance test. Main outcome measures: One- and 2-hour post load plasma glucose level, HbA1c, and assessment of gastric emptying via an isotope breath test. Results: Thirty-five patients (12 females; mean age, 58.5 years [SD, 10.5]; mean HbA1c, 37.4 mmol/mol [SD, 7.0]) attended the followup. In 32/35 patients (91%) the 1-hour post load plasma glucose level was ≥ 8.6 mmol/L. There was a positive correlation between the plasma glucose level at 1 hour (r2 = 0.21; P = 0.006), but no correlation between the 2-hour glucose level (r2 = 0.006; P = 0.63) and gastric emptying. Conclusion: Glucose intolerance, when defined as 1-hour glucose level ≥ 8.6 mmol/L following a 75 g oral glucose load, persists at 3 months in most survivors of stress hyperglycaemia and is dependent on the rate of gastric emptying. Longitudinal studies to characterise mechanisms underlying dysglycaemia and progression to diabetes in individuals with stress hyperglycaemia are indicated.

Relationships of Glucose, GLP-1, and Insulin Secretion With Gastric Emptying After a 75-g Glucose Load in Type 2 Diabetes

CONTEXT

The relationships of gastric emptying (GE) with the glycemic response at 120 minutes, glucagon-like peptide-1 (GLP-1), and insulin secretion following a glucose load in type 2 diabetes (T2D) are uncertain.

OBJECTIVE

We evaluated the relationship of plasma glucose, GLP-1, and insulin secretion with GE of a 75-g oral glucose load in T2D.

DESIGN

Single-center, cross-sectional, post hoc analysis.

SETTING

Institutional research center.

PARTICIPANTS

43 individuals with T2D age 65.6 ± 1.1 years, hemoglobin A1c 7.2 ± 1.0%, median duration of diabetes 5 years managed by diet and/or metformin.

INTERVENTION

Participants consumed the glucose drink radiolabeled with 99mTc-phytate colloid following an overnight fast. GE (scintigraphy), plasma glucose, GLP-1, insulin, and C-peptide were measured between 0 and 180 minutes.

MAIN OUTCOME MEASURES

The relationships of the plasma glucose at 120 minutes, plasma GLP-1, and insulin secretion (calculated by Δinsulin0-30/ Δglucose0-30 and ΔC-peptide0-30/Δglucose0-30) with the rate of GE (scintigraphy) were evaluated.

RESULTS

There were positive relationships of plasma glucose at 30 minutes (r = 0.56, P < 0.001), 60 minutes (r = 0.57, P < 0.001), and 120 minutes (r = 0.51, P < 0.001) but not at 180 minutes (r = 0.13, P = 0.38), with GE. The 120-minute plasma glucose and GE correlated weakly in multiple regression models adjusting for age, GLP-1, and insulin secretion (P = 0.04 and P = 0.06, respectively). There was no relationship of plasma GLP-1 with GE. Multiple linear regression analysis indicated that there was no significant effect of GE on insulin secretion.

CONCLUSION

In T2D, while insulin secretion is the dominant determinant of the 120-minute plasma glucose, GE also correlates. Given the relevance to interpreting the results of an oral glucose tolerance test, this relationship should be evaluated further. There appears to be no direct effect of GE on either GLP-1 or insulin secretion.