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25-05-2010 | Diabetes | Article

Blood glucose and HbA1c only modestly linked to CHD risk in nondiabetics

Abstract

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MedWire News: Increased levels of fasting and post-load glucose and glycated hemoglobin (HbA1c) only modestly increase coronary heart disease (CHD) risk in nondiabetics, show results from the Reykjavik study and a meta-analysis of the literature.

Previous research has demonstrated that good blood glucose control is important in patients with diabetes to reduce the risk for heart disease as well as other complications, but whether high blood glucose or HbA1c increases the risk for CHD in nondiabetic people is less certain.

Nadeem Sarwar (University of Cambridge, UK) and colleagues studied data on 18,569 Icelandic people enrolled in the population-based Reykjavik study.

Over a mean follow-up period of 23.5 years, 4664 incident cases of CHD (nonfatal myocardial infarction [MI] or fatal CHD) were recorded. Of these participants, 4490 had no history of diabetes at baseline.

The team found that people with no known diabetes at baseline, but a fasting plasma glucose (FPG) level of 7.0 mmol/l or more, had a 2.37-fold increased risk for CHD compared with individuals with FPG below 7.0 mmol/l.

For people with FPG below 7.0 mmol/l there was no significant CHD risk associated with higher FPG and a marginally significant 3% increase in relative risk for CHD associated with each 1.0 mmol/l increase in post-load glucose.

Sarwar and co-authors also carried out a meta-analysis of 26 additional relevant studies that assessed CHD risks associated with increases in FPG (23 studies; n=255,171), post-load glucose (15 studies; n=102,382), or HbA1c (nine studies; n=49,099). Participants with known diabetes or a FPG of 7.0 mmol/l or more were excluded.

They an increase of 1.0 mmol/l in FPG or post-load glucose or an increase of 1% in HbA1c were associated with increases of 6%, 5%, and 20%, respectively, in the risk for CHD.

“In this prospective cohort and wider meta-analysis, the researchers did not find evidence of a strong or continuous association between blood sugar levels [fasting and post-load glucose levels] and risk of heart disease amongst people without diabetes,” write Sarwar et al in the journal PLoS Medicine.

“Associations of HbA1c with CHD risk in such people appeared somewhat stronger,” they add.

They conclude: “Scientific guidelines, policies, and trial designs premised on the existence of strong, log-linear associations of fasting and post-load glucose concentration with CHD risk may benefit from review in light of these epidemiological findings.”

MedWire (www.medwire-news.md) is an independent clinical news service provided by Current Medicine Group, a trading division of Springer Healthcare Limited. © Springer Healthcare Ltd; 2010

By Helen Albert