(P29-028-23) Dietary Calcium Intake and Incident Type 2 Diabetes Mellitus: The REGARDS Cohort Study

Objectives: Epidemiological evidence suggests dietary calcium (Ca) intake may have a protective effect on type 2 diabetes mellitus (T2DM) development, however, findings vary by population. We aimed to investigate the association of dietary Ca intake with incidence of T2DM in middle-aged and older American adults.

Methods: Participants were from the REasons for Geographic and Racial Differences in Stroke (REGARDS) cohort. A total of 10,630 non-diabetic participants (age: 63.2±8.6 years) with available data on dietary calcium intake and the follow-up visit for diabetes diagnosis were included. Dietary Ca intake (from diet and supplements) were collected at baseline (2003-2007) using the modified Block 98 food frequency questionnaire and were adjusted by total energy intake (per 1000 kcal/d). Incident T2DM was defined as fasting glucose ≥ 7.0 mmol/l, non-fasting glucose ≥ 11.1 mmol/l or diabetes medication use at the follow-up examination. A multivariable-adjusted logistic regression model was used to examine the associations of interest.

Results: During an average 10-year follow-up, 1,124 incident T2DM cases were identified. After adjustment for potential confounders, an inverse association trend between energy-adjusted dietary Ca intake and incidence of T2DM was observed. Comparing individuals in the highest quintile of dietary Ca intakes to those in the lowest group, the multivariable-adjusted odds ratio (OR) was 0.75 [95% confidence interval (CI)= 0.54, 1.04], and p for trend=0.02. The observed inverse association of dietary Ca intake with incident T2DM persisted among the Ca supplement users [quintile 5 (highest) vs. quintile 1 (lowest): OR=0.62, 95% CI=0.42, 0.90, p for trend=0.03], but not among non-users. Additionally, the inverse association among Ca supplement users remained after further adjusting for the Mediterranean Diet Score in the sensitivity analysis.

Conclusions: In this prospective cohort study, dietary Ca intake was inversely associated with the incidence of T2DM in Ca supplement users. The dose of Ca intake may, at least in part, explain the inconsistent findings among Ca supplement users and non-users. Further studies are needed to elucidate the underlying mechanism of action.

Funding Sources: This research project was supported by a grant from the National Institutes of Health.