The association between HbA1c, fasting glucose, 1-hour glucose and 2-hour glucose during an oral glucose tolerance test and cardiovascular disease in individuals with elevated risk for diabetes

PLoS One. 2014 Oct 6;9(10):e109506. doi: 10.1371/journal.pone.0109506. eCollection 2014.

Abstract

Objective: To determine the association between HbA1c, fasting plasma glucose (FPG), 1-hour (1 hPG) and 2-hour (2 hPG) glucose after an oral glucose tolerance test (OGTT) and cardiovascular disease in individuals with elevated risk for diabetes.

Design: We studied the relationship between baseline, updated mean and updated (last) value of HbA1c, FPG, 1 hPG and 2 hPG after an oral 75 g glucose tolerance test (OGTT) and acute CVD events in 504 individuals with impaired glucose tolerance (IGT) at baseline enrolled in the Finnish Diabetes Prevention Study.

Setting: Follow-up of clinical trial.

Participants: 504 individuals with IGT were followed with yearly evaluations with OGTT, FPG and HbA1c.

Main outcome measure: Relative risk of CVD.

Results: Over a median follow-up of 9.0 years 34 (6.7%) participants had a CVD event, which increased to 52 (10.3%) over a median follow-up of 13.0 years when including events that occurred among participants following a diagnosis of diabetes. Updated mean HbA1c, 1 hPG and 2 hPG, HR per 1 unit SD of 1.57 (95% CI 1.16 to 2.11), p = 0.0032, 1.51 (1.03 to 2.23), p = 0.036 and 1.60 (1.10 to 2.34), p = 0.014, respectively, but not FPG (p = 0.11), were related to CVD. In analyses of the last value prior to the CVD event the same three glycaemic measurements were associated with the CVD events, with HRs per 1 unit SD of 1.45 (1.06 to 1.98), p = 0.020, 1.55 (1.04 to 2.29), p = 0.030 and 2.19 (1.51 to 3.18), p<0.0001, respectively but only 2 hPG remained significant in pairwise comparisons. Including the follow-up period after diabetes onset updated 2 hPG (p = 0.003) but not updated mean HbA1c (p = 0.08) was related to CVD.

Conclusions and relevance: Current 2 hPG level in people with IGT is associated with increased risk of CVD. This supports its use in screening for prediabetes and monitoring glycaemic levels of people with prediabetes.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Blood Glucose / analysis*
  • Cardiovascular Diseases / blood
  • Cardiovascular Diseases / epidemiology*
  • Cardiovascular Diseases / prevention & control
  • Fasting / blood*
  • Female
  • Follow-Up Studies
  • Glucose Tolerance Test*
  • Glycated Hemoglobin A / analysis*
  • Humans
  • Life Style
  • Male
  • Middle Aged
  • Prediabetic State / blood*
  • Prediabetic State / epidemiology*
  • Prediabetic State / prevention & control
  • Risk
  • Time Factors

Substances

  • Blood Glucose
  • Glycated Hemoglobin A

Grant support

The current DPS analysis has been financially supported by the Academy of Finland, an unrestricted grant from AstraZeneca, an unrestricted grant from Novonordisk Scandinavia, Ministry of Education, Novo Nordisk Foundation, Yrjö Jahnsson Foundation, Juho Vainio Foundation, Finnish Diabetes Research Foundation, Finnish Foundation for Cardiovascular Research, and Competitive Research Funding from Tampere, Kuopio, and Oulu University Hospitals. The funders had no role in the design of the study, analysis of results, or the decision to submit the report.