Objective To study the clinical characteristics of senile type 2 diabetes mellitus(T2-DM) with concurrent acute myocardial infarction (AMI). MethodsNinety-four patients, over 60 years old and hospitalized from February 2008 to March 2011, were slividced into two groups: (1) Group A consisted of 51 patients with type 2 diabetes mellitus and concurrent acute myocardial infarction who received coronary arteriography (CAG). (2) Group B consisted of 51 patients without T2-DM who received CAG. The clinical manifestations and the coronary artery characteristics in both groups were analyzed and compared. ResultsBlood sugar in group A was （12.9±5.2） mmol/L and was （5.11±0.65） mmol/L (P<0.05)in group B.The average time from the onset to hospitalization was （46±32） hour for group A, and （12±7） hours for group B (P<0.01). In group A, 22(51%) had atypical chest pain and 12(28%) had non-chest pain while in group B, there were 9(18%) and 3 cases (6%), respectively (P<0.01). Group A had coronary artery degree Ⅲ narrowing in 20(46.5%) and degree Ⅳ narrowing in 11(25.6%) while in group B there were 11(21.6%) and 4 cases (7.8%) respectively (P<0.01). Eight patients in group A died (18.6%) after 4 weeks of hospitalization and  3 patients (5.9%) in group B(P<0.05). ConclusionsIn elder patients with T2-DM and concurrent AMI, the atypical symptoms or lack of symptoms can cause delayed hospitalization. Their blood sugar level and fatality rate are high, complications are numerous, cardiac function is bad, and pathological changes in coronary arteries are severe.