High risk of cardiovascular mortality in individuals with impaired fasting glucose is explained by conversion to diabetes: the Hoorn study.
OBJECTIVE
To optimize identification of future diabetic patients, the American Diabetes Association (ADA) introduced criteria for impaired fasting glucose (IFG) in 1997 (IFG 6.1 mmol/l [IFG6.1]) and lowered the threshold from 6.1 to 5.6 mmol/l (IFG5.6) in 2003. Our aim was to assess the consequences of lowering the IFG cutoff on the risk of cardiovascular disease (CVD) mortality and to evaluate whether this risk is explained by a conversion to type 2 diabetes within 6.4 years.


METHODS
In a population-based cohort, the Hoorn Study, plasma glucose was determined in 1989 and 1996 (n = 1,428). Subjects were classified in 1989 according to 1997 and 2003 ADA criteria. Subjects with IFG in 1989 were further classified according to diabetes status in 1996. Hazard ratios for CVD mortality (n = 81) in the period 1996-2005 were adjusted for age and sex.


RESULTS
Subjects with IFG6.1, but not IFG5.6, had a significantly higher CVD mortality risk than normal fasting glucose (NFG) subjects. Subjects who converted from IFG to diabetes (IFG6.1: 42%; IFG5.6: 21%) had a more than twofold risk of CVD mortality (IFG6.1: 2.47 [1.17-5.19]; IFG5.6: 2.14 [1.12-4.10]) than subjects with NFG. IFG subjects who did not develop diabetes did not have significantly higher CVD mortality risks (IFG6.1: 1.50 [0.72-3.15]; IFG5.6: 1.15 [0.69-1.93]).


CONCLUSIONS
The lower cutoff for IFG (ADA 2003 criteria) results in a category of IFG that no longer represents a high-risk state of CVD. Furthermore, only subjects who convert from IFG to diabetes have a high risk of CVD mortality.
Rijkelijkhuizen
Josina M
JM
EMGO Institute, VU University Medical Center, Van der Boechorststraat 7, 1081 BT Amsterdam, Netherlands. j.rijkelijkhuizen@vumc.nl
Nijpels
Giel
G
Heine
Robert J
RJ
Bouter
Lex M
LM
Stehouwer
Coen D A
CD
Dekker
Jacqueline M
JM
D000368:Aged; D015992:Body Mass Index; D002318:Cardiovascular Diseases / Q000401:mortality*; D002648:Child; D003920:Diabetes Mellitus / Q000453:epidemiology*; D005215:Fasting; D005260:Female; D018149:Glucose Intolerance / Q000453:epidemiology*; D006801:Humans; D008074:Lipoproteins / Q000097:blood; D008875:Middle Aged; D009426:Netherlands / Q000453:epidemiology; D012307:Risk Factors
D008074:Lipoproteins