the study protocol was approved by the tianjin hospital ethics committee , and informed consent of all patients was obtained .
the inclusion criteria were 1 ) the injury time of hip fractures was < 24 h before admission and fracture diagnosis by x - ray examinations in our emergency department , 2 ) patient participated in physical examinations each year and blood glucose was normal ( < 6.1 mmol / l ) with ordinary values of glycosylated hemoglobin ( hba1c ) , 3 ) a pair of lower limb venous vascular ultrasound examinations confirmed no deep venous thromboembolism ( dvt ) , 4 ) osteoporosis was confirmed by bone density examination , and 5 ) orthopedic surgery was not completed within 1 week after admission to the hospital or no operation was performed ( conservative treatment ) .
the exclusion criteria were 1 ) the time of hip fracture injury was > 24 h before admission ; 2 ) diagnosed type 1 or type 2 diabetes ; 3 ) need of emergency operation within 1 week after hip fracture ; 4 ) the occurrence of dvt , pulmonary embolism , or thyroid disease ; and 5 ) renal / liver failure .
blood and urine routine , liver and kidney function , calcium , phosphorus , and serum cardiac enzyme concentrations , insulin level , and serum lipids were tested after admission .
electrocardiography ( ecg ) , cardiorespiratory function test , ultrasonic cardiography , chest x - ray , lower limb venous vascular ultrasound , and bone mineral density measurements of the bilateral hip were conducted .
closed reduction , bone traction treatments , and prevention of dvt were administered to all patients with hip fractures on the day of admission ( 10 ) and they continued to take their cardiac medications .
all patients who met the inclusion criteria were recorded with a standardized form throughout the study course .
the fasting blood glucose ( fbg ) was examined at 6:00 a.m. every morning from the 1st to the 7th day after admission , and ecgs were measured at admission and from the 1st to the 7th day after admission at 10:00 a.m. every morning . if clinical symptoms indicated and/or electrocardiographic changes suggested a myocardial infarction , additional blood samples were drawn from the antecubital vein in order to examine creatine kinase ( ck ) , ck - mb isoenzyme , and troponin - i values .
ami diagnosis criteria met at least two of following : 1 ) the ck - mb isoenzyme and/or troponin - i concentration elevated above the hospital laboratory 's myocardial infarction threshold ; 2 ) persistent st - t segment changes , new q waves , or left bundle branch block occurred ; 3 ) serious precordial chest pain lasting for 30 min or more .
stress hyperglycemia diagnosis criteria were as follows : 1 ) patients did not have a previous diabetes history , 2 ) admission or in - hospital fasting plasma glucose levels of 7 mmol / l or more in two or more tests ( 13 ) , and 3 ) normal hba1c values .
, chicago , il ) software was applied by a professional statistician to complete the analyses .
the period of follow - up interviews was 3 months after discharge , and mortality was recorded by the investigators via telephone calls and/or outpatient clinic visits .
consecutive hip fracture patients ( n = 1,257 ) were selected for the analysis during a 5-year period from february 2007 to february 2012 .
the study protocol was approved by the tianjin hospital ethics committee , and informed consent of all patients was obtained .
the inclusion criteria were 1 ) the injury time of hip fractures was < 24 h before admission and fracture diagnosis by x - ray examinations in our emergency department , 2 ) patient participated in physical examinations each year and blood glucose was normal ( < 6.1 mmol / l ) with ordinary values of glycosylated hemoglobin ( hba1c ) , 3 ) a pair of lower limb venous vascular ultrasound examinations confirmed no deep venous thromboembolism ( dvt ) , 4 ) osteoporosis was confirmed by bone density examination , and 5 ) orthopedic surgery was not completed within 1 week after admission to the hospital or no operation was performed ( conservative treatment ) .
the exclusion criteria were 1 ) the time of hip fracture injury was > 24 h before admission ; 2 ) diagnosed type 1 or type 2 diabetes ; 3 ) need of emergency operation within 1 week after hip fracture ; 4 ) the occurrence of dvt , pulmonary embolism , or thyroid disease ; and 5 ) renal / liver failure .
blood and urine routine , liver and kidney function , calcium , phosphorus , and serum cardiac enzyme concentrations , insulin level , and serum lipids were tested after admission .
electrocardiography ( ecg ) , cardiorespiratory function test , ultrasonic cardiography , chest x - ray , lower limb venous vascular ultrasound , and bone mineral density measurements of the bilateral hip were conducted .
closed reduction , bone traction treatments , and prevention of dvt were administered to all patients with hip fractures on the day of admission ( 10 ) and they continued to take their cardiac medications .
all patients who met the inclusion criteria were recorded with a standardized form throughout the study course .
the fasting blood glucose ( fbg ) was examined at 6:00 a.m. every morning from the 1st to the 7th day after admission , and ecgs were measured at admission and from the 1st to the 7th day after admission at 10:00 a.m. every morning . if clinical symptoms indicated and/or electrocardiographic changes suggested a myocardial infarction , additional blood samples were drawn from the antecubital vein in order to examine creatine kinase ( ck ) , ck - mb isoenzyme , and troponin - i values .
ami diagnosis criteria met at least two of following : 1 ) the ck - mb isoenzyme and/or troponin - i concentration elevated above the hospital laboratory 's myocardial infarction threshold ; 2 ) persistent st - t segment changes , new q waves , or left bundle branch block occurred ; 3 ) serious precordial chest pain lasting for 30 min or more .
stress hyperglycemia diagnosis criteria were as follows : 1 ) patients did not have a previous diabetes history , 2 ) admission or in - hospital fasting plasma glucose levels of 7 mmol / l or more in two or more tests ( 13 ) , and 3 ) normal hba1c values .
chicago , il ) software was applied by a professional statistician to complete the analyses .
the period of follow - up interviews was 3 months after discharge , and mortality was recorded by the investigators via telephone calls and/or outpatient clinic visits .
patients ( n = 1,257 ) who met the inclusion criteria were enrolled in this clinical observation . among the patients , the average age was 75.20  7.71 years and 64.52% were women .
the most prevalent comorbidity was hypertension ( 57.68% ) , followed by coronary artery disease ( cad ) or family history of cad ( 49.90% ) , dyslipidemia ( elevation of ldl cholesterol [ ldl - c ] , 49.27% ; triglyceride , 39.14% ; and low levels of hdl cholesterol [ hdl - c ] , 21.40% ) , obesity ( 37.63% ) , and smoking ( 28.16% ) .
the frequency of stress hyperglycemia was 47.89% ( 602/1,257 ) and that of ami was 9.31% ( 117/1,257 ) .
figure 1 shows the correlation between time of fracture and fbg . in the stress hyperglycemia group ,
repeated anovas showed that at each time point in the stress hyperglycemia group , the blood glucose values were significantly different ( p < 0.05 ) , whereas in the non - hyperglycemia patients , they did not change ( p = 0.10 ) ( fig .
the incidence of ami in the stress hyperglycemia group was significantly higher ( 12.46% [ 75/602 ] ) than in the non - hyperglycemia group ( 6.41% [ 42/655 ] , p < 0.05 ) .
the number of amis was correlated with the occurrence of hyperglycemia and was significantly higher 3 days after injury in the hyperglycemia group ( p < 0.05 ) , whereas the temporal distribution of ami in the non - hyperglycemia group was not different between 3 and > 3 days after injury ( table 2 ) . in all patients with ami
, nstemi events occurred more often than stemi ( 62.39% [ 73/117 ] vs. 37.61% [ 44/117 ] ) , but stemi significantly prevailed in the stress hyperglycemia group ( p < 0.05 ) . in table 3 , risk factors for ami and their significance are listed . a multiple logistic regression analysis using a forward stepwise ( conditional ) method revealed that stress hyperglycemia is an independent risk factor for the development of ami ( relative risk [ rr ] 2.130 [ 95% ci 1.4313.172 ] ) .
patients with stress hyperglycemia after hip fracture were 2.130-fold more likely to develop an ami than the non - hyperglycemia individuals .
characteristics of myocardial infarction in the two groups at the end of 3 months follow - up , there were no differences in mortality in patients with versus without stress - induced hyperglycemia ( 6.98% [ 42/602 ] vs. 4.43% [ 29/655 ] , p = 0.051 ) .
in our study , we found that the frequency of stress hyperglycemia was 47.89% and the incidence of ami was 9.31% in patients after hip fractures .
the incidence of ami in the stress hyperglycemia group was 12.46% , whereas the overall ami incidence in patients without hip fractures in china is 2.6% ( 14 ) , indicating that the incidence of ami in patients after hip fractures appears higher than overall ami incidence in china .
others have reported that the increased incidence of ami after hip fracture was related to osteoporosis ( 4,14 ) .
osteoporosis and cardiovascular diseases share common risk factors like poor general health status , lifestyle , nutrition , hormone secretion , vitamin d deficiency , systemic inflammation - related ( e.g. , c - reactive protein , interleukin-6 , or tumor necrosis factor ) diseases , and medications through different mechanisms both in bone and arteries ( 1525 ) .
patients with osteoporotic fractures are likely to have coexisting blood vessel diseases , but in our study , we found that particularly stress hyperglycemia plays a vital role , because the incidence of ami in the stress hyperglycemia group was 2.130 higher than in the non - hyperglycemia group . in patients with hip fractures ,
stress hyperglycemia was the sole significant independent risk factor for the development of ami ( 95% ci 1.4313.172 ) .
acute fractures induce stress hormone secretion of glucocorticoid , glucagon , adrenaline , thyroxin , somatotropin , and others , which is called the  stress response .
 during the stress response , activation of serial hormones induces insulin resistance , resulting in hyperglycemia and the associated risk factors present then in patients with acute traumata ( 26 ) .
it is well known that stress hyperglycemia is associated with oxidative stress , inflammatory responses , damaging of coronary microcirculation , and markedly worsened signal transduction pathways of endogenous cardioprotective responses .
hyperglycemia can induce adp - induced platelet aggregation and increase plasma catecholamine , which is associated with vulnerable plaque evolution , the promotion of microcircular dysfunctions , and thrombogenesis ( 2737 ) .
our present work indicates that for patients without a history of diabetes , stress - induced hyperglycemia plays a key role in the risk of developing ami .
our present analysis revealed that most ( 62.67% [ 47/75 ] ) amis occurred within the first 3 days after hip fractures , which is in accordance with the literature ( 2 ) . in the stress hyperglycemia group ,
blood glucose peaked at 23 days after hip fracture and then declined gradually , indicating a coincidence of ami with the peak time of fbg .
the cause of a more frequent stemi occurrence in stress - induced hyperglycemia might be that raised glucose levels contribute to platelet activation and thereby enhanced platelet - mediated thrombogenesis ( 38 ) , which develops into completely occlusive thrombi .
in addition , our study showed stress hyperglycemia ranges of 6.19.7 mmol / l after hip fractures for the first time , and we recommend that stress - induced hyperglycemias after hip fracture should be identified early .
a limitation of our study was that we did not investigate an effect of inflammatory factors and/or stress hormones on fbg levels , which lead to increased ami risk .
in addition , we did not compare the results of this study with patients suffering from diabetes , and we did not find differences between the stress hyperglycemia and no hyperglycemia groups regarding comorbid disorders and/or drug administrations , e.g. , statin against hypertension .
therefore we can not completely rule out that other factors also contributed to the incidence of myocardial infarctions .
moreover , patients were not accurately diagnosed for diabetes in the longer term , and because blood glucose levels largely fluctuate , we did not specifically treat the hyperglycemias . up until now , there has been no clear agreement on whether it is necessary to control glucose levels in these patients .
in addition , we only show the significance of hyperglycemia on the incidence of ami during admission ; we did not show clinical outcome data at follow - up .
however , this study underlines the importance of understanding the indication for adopting appropriate methods to identify stress - induced hyperglycemia in correlation with ami after hip fracture .
we recommend that in patients , even without previous diabetes , fbgs and ecgs should be monitored for at least the first 7 days after hip fractures .
this might be helpful for the endocrinologist , cardiologist , and orthopedic surgeon to timely detect amis .
we conclude that stress - induced hyperglycemia increased the risk of ami in patients with hip fractures .
 objectiveto investigate the risk of acute myocardial infarction ( ami ) following stress hyperglycemia after hip fracture.research design and methodsfrom february 2007 to february 2012 , we carried out a prospective observational analysis of 1,257 consecutive patients with no history of diabetes who suffered hip fractures . 
 fasting blood glucose ( fbg ) and glycosylated hemoglobin tests as well as electrocardiography , ultrasonic cardiography , and chest x - ray examinations were performed after admission . 
 all selected hip fracture patients were divided into stress hyperglycemia and non - hyperglycemia groups according to their fbg , and the incidence of ami was monitored.resultsamong the patients enrolled , the frequency of stress hyperglycemia was 47.89% ( 602/1,257 ) and that of ami was 9.31% ( 117/1,257 ) , and the occurrence of ami in the stress hyperglycemia group was higher than in the non - hyperglycemia group ( 12.46 vs. 6.41% , p < 0.05 ) . in the stress 
 hyperglycemia patients , fbg reached maximum levels at 23 days after hip fractures and then decreased gradually . the ami incidence ( 62.67% [ 47/75 ] ) of 
 the stress hyperglycemia group was highest in the initial 3 days after hip fracture , significantly coinciding with the fbg peak time ( p < 0.05 ) . in all patients with ami , 
 non  
 st - segment elevation myocardial infarction occurred more often than st - segment elevation myocardial infarction ( 62.39% [ 73/117 ] vs. 37.61% [ 44/117]).conclusionsstress - induced hyperglycemia after hip fracture increased the risk of ami . 