A CROSS-SECTIONAL STUDY OF THE ASSOCIATION BETWEEN THE 1-HOUR ORAL GLUCOSE TOLERANCE TEST AND THE METABOLIC SYNDROME IN A HIGH-RISK SAMPLE WITH IMPAIRED FASTING GLUCOSE

Prediabetes and Cardiometabolic Risk: The Need for Improved Diagnostic Strategies and Treatment to Prevent Diabetes and Cardiovascular Disease

The progression from prediabetes to type-2 diabetes depends on multiple pathophysiological, clinical, and epidemiological factors that generally overlap. Both insulin resistance and decreased insulin secretion are considered to be the main causes. The diagnosis and approach to the prediabetic patient are heterogeneous. There is no agreement on the diagnostic criteria to identify prediabetic subjects or the approach to those with insufficient responses to treatment, with respect to regression to normal glycemic values or the prevention of complications. The stratification of prediabetic patients, considering the indicators of impaired fasting glucose, impaired glucose tolerance, or HbA1c, can help to identify the sub-phenotypes of subjects at risk for T2DM. However, considering other associated risk factors, such as impaired lipid profiles, or risk scores, such as the Finnish Diabetes Risk Score, may improve classification. Nevertheless, we still do not have enough information regarding cardiovascular risk reduction. The sub-phenotyping of subjects with prediabetes may provide an opportunity to improve the screening and management of cardiometabolic risk in subjects with prediabetes.

Saving time by replacing the standardised two-hour oral glucose tolerance test with a one-hour test: Validation of a new screening algorithm in patients with coronary artery disease from the ESC-EORP EUROASPIRE V registry

AIMS

An oral glucose tolerance test (OGTT) combining fasting (FPG) and 2-hour plasma glucose (2hPG) is the most sensitive method for detecting type 2 diabetes (T2DM). Since it is considered time-consuming, we aim at validating a previously proposed screening algorithm based on a 1-hour plasma glucose (1hPG) with a 12 mmol/L threshold.

METHODS

Nine-hundred-eighteen patients with coronary artery disease (CAD) without known T2DM from the EUROASPIRE V cross-sectional survey underwent an OGTT. The reference for T2DM was 2hPG ≥ 11.1 mmol/L. T2DM diagnosis by HbA1c ≥ 6.5%(48 mmol/mol), FPG ≥ 7.0 mmol/L, and 1hPG ≥ 12 mmol/L were compared with the outcome of 2hPG.

RESULTS

Mean FPG, HbA1c and 2hPG were 6.1 mmol/L, 5.6%(38 mmol/mol) and 7.8 mmol/L respectively. Ninety-six patients (10%) were diagnosed with T2DM according to 2hPG. Using this definition, in the group with FPG < 6.5 mmol/L and 1hPG < 12 only 5 (1%) were misdiagnosed as false negatives. All patients with a FPG > 8.0 mmol/L and 1hPG > 15.0 mmol/L were identified as having T2DM. According to the algorithm, in 79% of patients T2DM could be excluded by combining FPG < 6.5 mmol/L and 1hPG < 12 mmol/L.

CONCLUSIONS

T2DM Screening by means of an algorithm combining FPG and 1hPG limits the demand of a 2hOGTT in 79% of CAD patients without known T2DM. HbA1c did not add to the information derived from this algorithm.

The Oral Glucose Tolerance Test: 100 Years Later

For over 100 years, the oral glucose tolerance test (OGTT) has been the cornerstone for detecting prediabetes and type 2 diabetes (T2DM). In recent decades, controversies have arisen identifying internationally acceptable cut points using fasting plasma glucose (FPG), 2-h post-load glucose (2-h PG), and/or HbA1c for defining intermediate hyperglycemia (prediabetes). Despite this, there has been a steadfast global consensus of the 2-h PG for defining dysglycemic states during the OGTT. This article reviews the history of the OGTT and recent advances in its application, including the glucose challenge test and mathematical modeling for determining the shape of the glucose curve. Pitfalls of the FPG, 2-h PG during the OGTT, and HbA1c are considered as well. Finally, the associations between the 30-minute and 1-hour plasma glucose (1-h PG) levels derived from the OGTT and incidence of diabetes and its complications will be reviewed. The considerable evidence base supports modifying current screening and diagnostic recommendations with the use of the 1-h PG. Measurement of the 1-h PG level could increase the likelihood of identifying high-risk individuals when the pancreatic ß-cell function is substantially more intact with the added practical advantage of potentially replacing the conventional 2-h OGTT making it more acceptable in the clinical setting.