Egg, cholesterol and protein intake and incident type 2 diabetes mellitus: Results of repeated measurements from a prospective cohort study

Abstract

Epidemiological evidence on the associations of egg, cholesterol and protein intake with risk of type 2 diabetes is inconsistent. Therefore, we conducted this study to explore these associations among Chinese adults. Data from 4 waves (2004, 2006, 2009 and 2011) of the China Health and Nutrition Survey were used. A multistage random-cluster sampling method was employed to recruit the participants in both rural and urban areas. We included individuals who participated in 2004 and any waves afterwards. Those 1) below 18 years of age; 2) with diabetes at baseline; or 3) with extreme energy intake (men: <800kcal or >6000kcal; women: <600kcal or >4000kcal) were excluded. Respondents were classified into four groups according to quartiles of egg, cholesterol and protein intake per day. Numbers of eggs per day were calculated by dividing egg intake in grams by 50g. Diagnosis of type 2 diabetes was self-reported. Logistic generalized estimation equation models were employed. There were 7312 individuals included in 2004, 6390 in 2006, 4826 in 2009 and 4963 in 2011. The mean age of participants at baseline was 48.3 years and 47.2% were men. Over an average of 5.8-y follow-up, 209 developed type 2 diabetes. After adjustment for demographic, lifestyle and dietary confounders, the odds ratio of type 2 diabetes for those in the highest compared with the lowest protein intake quartile was 2.38 (95% CI: 1.43, 3.98). The odds ratio of individuals with ≥3 eggs/day versus none was 3.76 (95% CI, 2.05, 6.90). Cholesterol intake was not associated with type 2 diabetes. Individuals with the highest protein intake had over a 2-fold increased risk of type 2 diabetes compared with those with the lowest protein intake. A high intake of egg, but not dietary cholesterol, was associated with type 2 diabetes. This association warrants further investigation.