Introduction 1 3 2 3 4 8 4 5 7 4 8 The aim of the present study was to compare short- and long-term mortality after a first hospitalized AMI in patients with and without DM encompassing the entire country by using data from linked national registers. Methods Design 9 10 10 10 Data analysis Survival time was calculated as the time from the initial AMI admission date in 1995 to the date of death from any cause, or a patient was censored at the date of loss to follow-up in the population register (4% of patients, e.g. in case of emigration) or the end of study at December 31, 2000, whichever came first. Crude short-term (28-day), 1-year and long-term (5-year) mortality risks were computed for diabetic and nondiabetic patients. Cox proportional hazard analyses were used to examine the association between DM and overall survival in men and women. DM (yes/no) and other predictors, including age (continuous), previous cardiovascular disease (yes/no) and ethnic origin (native or non-native Dutch) were included in the models. Furthermore, Cox proportional hazards models were used to determine whether gender, age, previous cardiovascular disease and ethnic origin were independently associated with overall survival in patients with DM and patients without DM. Interaction terms were included in the models to assess the interaction of gender with DM, age with DM and age with gender. Results 1 Table 1 Characteristics of first acute myocardial infarction patients with and without diabetes mellitus  Patients with diabetes mellitus Patients without diabetes mellitus Men Women Men Women Number of patients 969 1,049 13,494 6,053 Age at admission (years)     Mean (standard deviation) 68.7 (11.0) 73.2 (10.3) 64.0 (12.3) 71.6 (12.0) Prior admission for CVD (%) 31.7 31.0 16.8 16.3 Type of hospital (%)     Academic 6.7 6.1 6.2 5.7     General 93.3 93.9 93.8 94.3 Length of stay (days)     Mean (standard deviation) 11.1 (8.5) 12.5 (11.8) 9.7 (7.4) 10.6 (9.7)     Median 10.0 10.0 9.0 9.0 a 7.0–13.0 6.0–16.0 6.0–12.0 6.0–13.0 Native ethnic origin (%) 87.0 88.0 90.0 90.0 CVD = cardiovascular disease, excluding acute myocardial infarction a During admission, 18% of the diabetic patients (men 16%, women 20%) and 13% of the nondiabetic patients (men 11%, women 18%) died. In both diabetic and nondiabetic patients, AMI was the most frequent cause of death (during hospitalization 71 and 82%, respectively, and during 5 years of follow-up 39 and 45%, respectively). 2 Table 2 Short- and long-term mortality in patients with a first hospitalized acute myocardial infarction (AMI) in the Netherlands in 1995 stratified by gender and presence of diabetes mellitus Men n n n Deaths (%) n Deaths (%) At 28 days 170 17.5 (15.1–19.9) 1,555 11.5 (11.0–12.1) At 1 year 289 29.8 (26.9–32.7) 2,316 17.2 (16.5–17.8) At 5 years 516 53.3 (50.1–56.4) 4,116 30.5 (29.7–31.3) Women n n Deaths (n) Deaths (%) Deaths (n) Deaths (%) At 28 days 235 22.4 (19.9–24.9) 1,152 19.0 (18.0–20.0) At 1 year 368 35.1 (32.2–38.0) 1,626 26.9 (25.7–28.0) At 5 years 611 58.2 (55.3–61.2) 2,538 41.9 (40.7–43.2) Figures are numbers and percentages of deaths (95% confidence intervals in brackets) based on actuarial life table method 3 Table 3 Multivariate analysis of the association between diabetes mellitus and short- and long-term mortality in first acute myocardial infarction patients (n = 21,565) by gender and age  Age (years) Follow-up duration 28 days 1 year 5 years Men <60 1.41 (0.79–2.53) 1.38 (0.86–2.23) 1.83 (1.34–2.51) 60–69 1.46 (1.02–2.08)  1.73 (1.31–2.28) 1.80 (1.46–2.21) 70–79 1.04 (0.80–1.36) 1.16 (0.94–1.42) 1.42 (1.23–1.65) ≥80 1.11 (0.82–1.50) 1.32 (1.04–1.66) 1.37 (1.14–1.65) All ages 1.16 (0.99–1.36) 1.33 (1.17–1.50) 1.49 (1.36–1.64) Women <60 2.06 (1.09–3.88) 2.16 (1.25–3.75) 2.13 (1.40–3.25) 60–69 1.38 (0.92–2.06) 1.65 (1.19–2.29) 1.99 (1.57–2.54) 70–79 0.94 (0.72–1.22) 1.12 (0.92–1.37) 1.38 (1.19–1.60) ≥80 1.15 (0.94–1.42) 1.18 (0.99–1.40) 1.25 (1.09–1.44) All ages 1.12 (0.97–1.28) 1.23 (1.09–1.37) 1.39 (1.27–1.52) Total All ages 1.13 (1.02–1.26) 1.27 (1.17–1.38) 1.44 (1.35–1.53) Figures are hazard ratios (95% confidence intervals in brackets) with nondiabetic patients representing the reference group Results from Cox proportional hazards analyses with diabetes mellitus, previous cardiovascular disease and ethnic origin (age- and gender-specific hazard ratios) and age (gender-specific overall hazard ratios) and gender (overall hazard ratios) included in the model In the multivariate analyses, gender differences in mortality in nondiabetic patients varied over time with a higher mortality in women at 28 days and a higher mortality in men at 5 years (28-day HR 1.11; 95% CI 1.03–1.20, 5-year HR 0.93; 95% CI 0.88–0.98). Largely comparable, yet not significant, gender differences in mortality were found in diabetic patients (28-day HR 1.09; 95% CI 0.89–1.34, 5-year HR 0.93; 95% CI 0.82–1.04). Discussion Our study provides nationwide estimates of the difference in mortality after a first hospitalized AMI between diabetic and nondiabetic patients. Long-term mortality was significantly higher in diabetic patients than in nondiabetic patients. Yet, there were no significant differences in short-term mortality. Risks appeared to be equally elevated in men and women. Some aspects of the study need to be addressed. In our study, the presence of DM was merely based on information from hospital admissions and on a retrospective period of maximal 5 years. As a result, the estimate of the effect of DM is likely an overestimate due to selection of the more severe cases (those hospitalized with or due to DM), while a fairly limited number of people with less severe stages of DM (not requiring hospital care) will be diluted in the large group of people who truly did not have DM. 11 In our study, the percentage patients with a cardiovascular history (other than AMI) was about 2 times higher in diabetic patients than in nondiabetic patients. To be sure that the worse prognosis of diabetic patients compared to nondiabetic patients was real and not merely a reflection of the difference in cardiovascular history, we repeated the analyses in diabetic and nondiabetic patients without a cardiovascular history. These analyses yielded similar findings. 2 As data on patients without an AMI were not available, we were not able to compare the effect of DM on mortality in patients without an AMI with the effect in patients with an AMI, i.e. whether survival after an AMI is particularly worsened beyond the poorer prognosis already conferred by the presence of DM itself. 12 13 14 1 3 15 16 4 8 17 18 5 19 2 20 21 22 In conclusion, our findings in an unselected cohort covering a complete nation show that diabetic patients are at an increased risk of long-term mortality after a first acute myocardial infarction. Yet, there are no significant differences in short-term mortality. Risks appear to be equally elevated in men and women. These results stress the importance of secondary prevention by lifestyle advice and drugs in diabetic patients after a first AMI.