Dietary diversity no longer offsets the mortality risk of hyperhomocysteinaemia in older adults with diabetes: a prospective cohort study.

BACKGROUND AND

OBJECTIVE

The increased mortality risk of hyperhomocysteinaemia in diabetes may be mitigated by dietary quality.

METHODS AND STUDY

DESIGN

The Nutrition and Health Survey in Taiwan of 1999-2000 for elders formed this prospective cohort. Baseline health status, diet and anthropometry were documented and plasma homocysteine and biomarkers for B vitamins measured. Participants without diabetes (n=985) were referent for those who had diabetes or developed diabetes until 2006 (n=427). The effect of homocysteine on mortality risk during 1999-2008 was evaluated.

RESULTS

Men, smokers and those with poorer physical function had higher homocysteine, but less so with diabetes. Diabetes incidence was unrelated to homocysteine. In hyperhomocysteinaemia (>=15 vs <15 μmol/L), those with diabetes had an adjusted hazard ratio (HR) (95% CI) for mortality of 1.71 (1.18-2.46); p for interaction between homocysteine and diabetes was 0.005. Without diabetes, but with hyperhomocysteinaemia and a low dietary diversity score (DDS <=4 of 6), where the joint mortality hazard for the greater DDS, (>4) and lower homocysteine (<15) was referent, the HR was 1.80 (1.27-2.54) with significant interaction (p=0.008); by contrast, there was no joint effect with diabetes. The contribution of DDS to mortality mitigation in hyperhomocysteinaemia could not be explained by B group vitamins, even though plasma folate was low in hyperhomocysteinaemic participants. With hyperhomocysteinaemia, heart failure was a major cause of death.

CONCLUSIONS

In non-diabetic hyperhomocysteinaemia, a more diverse diet increases survival prospects independent of B group vitamins, but not in hyperhomocysteinaemic diabetes where the cardiomyopathy may be less responsive.