DALLAS – Women who embraced a healthy diet after being diagnosed with type 2 diabetes had significantly lower rates of all-cause and cardiovascular mortality than did those with a bad diet, in a large observational study with up to 26 years of follow-up.
"It’s never too late to improve your diet," Dr. Hyun Joon Shin said in presenting his analysis of data from the Nurses’ Health Study at the American Heart Association scientific sessions.
Dr. Hyun Joon Shin
The prospective observational Nurses’ Health Study began in 1976. It included 121,700 female American nurses aged 30-55 upon enrollment. Dr. Shin’s analysis included 8,354 women with no baseline cardiovascular disease, diabetes, or cancer who were diagnosed with type 2 diabetes during 1984-2006 and followed to June 2010.
During follow-up, there were 1,183 deaths in the cohort diagnosed with type 2 diabetes, including 491 deaths due to cardiovascular disease and 514 due to cancer.
Mortality risks were evaluated in relation to the extent to which the nurses adhered to a healthy, high-quality diet following their diagnosis of type 2 diabetes. The yardstick employed in evaluating eating patterns was the Alternative Healthy Eating Index–2010 (AHEI). The index, developed by researchers at Harvard University, scores patients’ consumption of various foods and nutrients known to be predictive of chronic disease risk, explained Dr. Shin of Baylor University Medical Center, Dallas.
There were 14.4 deaths per 1,000 persons per year in the top quintile in terms of adherence to the AHEI. A dose-response relationship was evident: The mortality rate was 28.8/1,000 persons per year among those in the bottom quintile, 23.1/1,000 in the second quintile, 19.3 in the third, and 20.7 in the fourth.
In a multivariate analysis adjusted for numerous potential confounders, including a participant’s prediabetic AHEI score, the diabetic nurses in the top quintile in terms of healthy eating had a 52% reduction in the risk of all-cause mortality compared with those in the lowest AHEI quintile. The healthiest eaters also had a 49% lower risk of cardiovascular mortality. However, their more modest 28% reduction in the risk of cancer-related death fell just short of statistical significance.
The AHEI, updated in 2010, awards points for increased consumption of whole grains, nuts, legumes, vegetables, fruits, fish or fish oil, and moderate alcohol intake. The index penalizes for consumption of red meat, processed meat products, trans fats, sodium, sugar-sweetened beverages, and fruit juices (J. Nutr. 2012;142:1009-18).
In examining the study findings more closely in terms of the impact of individual dietary components of the AHEI, Dr. Shin found nearly all of them had significant effects in multivariate analyses. For example, subjects in the top quintile for whole grain consumption had a 41% reduction in the risk of all-cause mortality compared with those in the bottom quintile, as well as a 33% reduction in the risk of cardiovascular mortality. Participants who drank the least amount of sugar-sweetened beverages had reductions in all-cause and cardiovascular mortality of 26% and 37%, compared with these rates for the quintile of biggest quaffers.
This was the first-ever postdiabetes dietary pattern analysis examining mortality in women with incident type 2 diabetes, according to Dr. Shin. The mechanism for the observed inverse relationship between diet quality and mortality is straightforward: A poor-quality diet is associated with increased risks of coronary heart disease, stroke, and weight gain and higher circulating levels of fasting insulin, inflammatory cytokines, and leptin, he said.
D. Shin’s study was supported by Baylor University research funding. He reported having no relevant financial conflicts.