Beta cell dysfunction in patients with acute myocardial infarction but without previously known type 2 diabetes: a report from the GAMI study.
OBJECTIVE
Patients with acute myocardial infarction (AMI) but without previously known type 2 diabetes have a high prevalence of undiagnosed IGT and type 2 diabetes. Such perturbations have dismal prognostic implications. The aim of this study was to characterise AMI patients in terms of insulin resistance and beta cell function.


METHODS
A total of 168 consecutive AMI patients were classified by means of an OGTT before hospital discharge as having NGT, IGT or type 2 diabetes. The homeostasis model assessment (HOMA-IR) was used to estimate insulin resistance. Beta cell responsiveness was quantified as insulinogenic index (IGI) at 30 min (DeltaI(30)/DeltaG(30)).


RESULTS
According to the HOMA-IR, patients with type 2 diabetes were more insulin resistant than those with IGT or NGT (p=0.003). Beta cell responsiveness deteriorated with decreasing glucose tolerance as measured by the IGI (median [quartile 1, quartile 3] in pmol/mmol: NGT, 70.1 [42.7, 101.4]; IGT, 48.7 [34.7, 86.8], type 2 diabetes, 38.1 [25.7, 61.6]; p<0.001). The IGI was significantly related to admission capillary blood glucose (r=-0.218, p=0.010) and to the area under the curve for glucose (r=-0.475, p<0.001).


CONCLUSIONS
Glucose abnormalities are very common in patients with AMI but without previously known type 2 diabetes. To a significant extent, this seems to be related to impaired beta cell function and implies that dysglycaemia immediately after an infarction is not a stress epiphenomenon but reflects stable disturbances of glucose regulation preceding the AMI. Early beta cell dysfunction may have important pathophysiological implications and may serve as a future target for treatment strategies.
Wallander
M
M
Department of Cardiology, Karolinska University Hospital Solna, Stockholm, Sweden. marit.wallander@medks.ki.se
Bartnik
M
M
Efendic
S
S
Hamsten
A
A
Malmberg
K
K
Ohrvik
J
J
Rydén
L
L
Silveira
A
A
Norhammar
A
A
D016022:Case-Control Studies; D003924:Diabetes Mellitus, Type 2 / Q000175:diagnosis* / Q000473:pathology; D005260:Female; D018149:Glucose Intolerance / Q000175:diagnosis; D038321:Glycemic Index; D006801:Humans; D007333:Insulin Resistance; D050417:Insulin-Secreting Cells / Q000473:pathology*; D008297:Male; D008875:Middle Aged; D009203:Myocardial Infarction / Q000150:complications / Q000188:drug therapy / Q000473:pathology*