Mortality trends in subjects with and without diabetes during 33 years of follow-up

Abstract

OBJECTIVE Mortality rates have declined substantially over the past decades in the general population, but the situation among diabetic subjects is less clear. The aim of this study was to analyze mortality trends in diabetic and nondiabetic subjects during 1972-2004. RESEARCH DESIGN AND METHODS Since 1972, all patients with diabetes are entered in a diabetes register at Laxå Primary Health Care Center; 776 incident cases were recorded up to 2001. The register has been supplemented with a nondiabetic population of 3,880 subjects and with data from the National Cause of Death Register during 1972 to 2004. RESULTS During the 33-year follow-up period, 233 (62.0%) diabetic women and 240 (60.0%) diabetic men and 995 (52.9%) nondiabetic women and 1,082 (54.1%) nondiabetic men died. The age-adjusted hazard ratio (HR) for all-cause mortality among diabetic and nondiabetic subjects was 1.17 (P < 0.0021) for all, 1.22 (P < 0.007) for women, and 1.13 (P = 0.095) for men. The corresponding cardiovascular disease (CVD) mortality HRs were 1.33 (P < 0.0001), 1.41 (P < 0.0003), and 1.27 (P < 0.0093), respectively. The CVD mortality reduction across time was significant in nondiabetic subjects (P < 0.0001) and in men with diabetes (P = 0.014) but not in diabetic women (P = 0.69). The results regarding coronary heart disease (CHD) were similar (P < 0.0001, P < 0.006, and P = 0.17, respectively). The CVD and CHD mortality rate change across time was fairly linear in all groups. CONCLUSIONS Diabetic subjects had less mortality rate reduction during follow-up than nondiabetic subjects. However the excess mortality risk for diabetic subjects was smaller than that found in other studies.

Figure 1

Cumulative mortality among diabetic and nondiabetic women and men during three time periods. A: Exposed diabetic (n = 131) and nondiabetic women (n = 655) 1972–1981. B: Exposed diabetic (n = 140) and nondiabetic women (n = 700) 1982–1991. C: Exposed diabetic (n = 105) and nondiabetic women (n = 525) 1992–2001. D: Exposed diabetic (n = 133) and nondiabetic men (n = 665) 1972–1981. E: Exposed diabetic (n = 154) and nondiabetic men (n = 770) 1982–1991. F: Exposed diabetic (n = 113) and nondiabetic men (n = 565) 1992–2001.

Figure 2

Proportion (%) not dead from CVD and CHD across the total study period among diabetic and nondiabetic women and men. A: CVD mortality among diabetic and nondiabetic women 1972–2001. B: CVD mortality among diabetic and nondiabetic men 1972–2001. C: CHD mortality among diabetic and nondiabetic women 1972–2001. D: CHD mortality among diabetic and nondiabetic men 1972–2001.