Joint Effects of Physical Activity and Diet Quality on Depression and Mortality in Diabetes

Minghui Wang3,621 enrolled

Overview

This observational study aims to investigate whether physical activity (PA) and diet quality (DQ) can reduce depression and mortality risk in individuals with diabetes. Participants will be adults diagnosed with diabetes during the 2007-2018 cycle of the National Health and Nutrition Examination Survey (NHANES). The main questions to be answered include: Does higher levels of physical activity significantly reduce the risk of depression in individuals with diabetes? Is higher diet quality associated with lower mortality in individuals with diabetes? Investigators will compare individuals with varying levels of PA and DQ to examine whether these two lifestyle factors, both individually and in combination, have protective effects on mental health and survival. Participants will: Complete questionnaires regarding their physical activity and dietary intake; Be assessed for depressive symptoms (PHQ-9); Be enrolled in long-term mortality follow-up (from the National Death Index); Analyses will be categorized according to their PA (measured in MET-min/week) and HEI-2015 dietary score.

Study Type

OBSERVATIONAL

Enrollment

3,621

Conditions

Diabetes Complications Depression Anxiety Disorder Diabetes

Eligibility

Sex: ALLMin age: 18 Years

Medical Language ↔ Plain English

Inclusion Criteria: * Adults aged 20 years and older. * Diagnosed with diabetes mellitus, defined by self-report, fasting plasma glucose ≥126 mg/dL, or HbA1c ≥6.5%. * Available data on physical activity, diet quality (HEI-2015), and depression status (PHQ-9). * Complete demographic and mortality follow-up data. Exclusion Criteria: * Missing key exposure or outcome data (e.g., physical activity, HEI-2015, PHQ-9, mortality). * Pregnant individuals at the time of the survey. * Participants with unreliable or extreme dietary intake data (e.g., energy intake \<500 or \>5000 kcal/day).

Outcomes

Primary Outcomes

Proportion of Adults With Diabetes Meeting Depression Criteria at Baseline (PHQ-9 ≥5)

Depression will be measured using the Patient Health Questionnaire-9 (PHQ-9), a validated 9-item self-report instrument scored from 0 to 27. Participants scoring ≥5 will be classified as having depressive symptoms. The outcome is the percentage of participants who meet this criterion at baseline.

Time frame: At the time of baseline NHANES examination for each 2-year survey cycle, including 2007-2008, 2009-2010, 2011-2012, 2013-2014, 2015-2016, and 2017-2018 (6 cycles in total, each lasting 2 years).

Secondary Outcomes

Odds Ratio for Depression by Physical Activity Category in Adults With Diabetes

Physical activity will be assessed using NHANES physical activity questionnaires and expressed in metabolic equivalent minutes per week (MET-min/week). Participants will be categorized into three PA levels: inactive (\<600 MET-min/week), insufficiently active (600-1,199 MET-min/week), and sufficiently active (≥1,200 MET-min/week). Depression will be measured using the Patient Health Questionnaire-9 (PHQ-9), a validated 9-item self-report instrument scored from 0 to 27, with scores ≥5 indicating the presence of depressive symptoms. Logistic regression models will be used to estimate odds ratios for depression across PA categories, using the inactive group as the reference.Odds Ratio (95% Confidence Interval)

Odds Ratio for Depression by Diet Quality Category in Adults With Diabetes

Diet quality will be assessed using the Healthy Eating Index-2015 (HEI-2015) score, derived from two 24-hour dietary recall interviews. Scores range from 0 to 100, with higher scores indicating better diet quality. Participants will be categorized into two groups: unqualified diet quality (HEI-2015 \<60) and qualified diet quality (HEI-2015 ≥60). Depression will be measured using the Patient Health Questionnaire-9 (PHQ-9), a validated 9-item self-report instrument scored from 0 to 27, with scores ≥5 indicating the presence of depressive symptoms. Logistic regression models will be used to estimate odds ratios for depression between diet quality groups, using the unqualified group as the reference.Odds Ratio (95% Confidence Interval)

Odds Ratio for Depression by Combined Physical Activity and Diet Quality Categories in Adults With Diabetes

Physical activity (PA) will be assessed using NHANES physical activity questionnaires and expressed in metabolic equivalent minutes per week (MET-min/week). Diet quality (DQ) will be assessed using the Healthy Eating Index-2015 (HEI-2015) score, derived from two 24-hour dietary recall interviews. Participants will be classified into four PA\_DQ groups: Inactive\_Unqualified (PA \<600 MET-min/week and HEI-2015 \<60) Inactive\_Qualified (PA \<600 MET-min/week and HEI-2015 ≥60) Active\_Unqualified (PA ≥600 MET-min/week and HEI-2015 \<60) Active\_Qualified (PA ≥600 MET-min/week and HEI-2015 ≥60) Depression will be measured using the Patient Health Questionnaire-9 (PHQ-9), a validated 9-item self-report instrument scored from 0 to 27, with scores ≥5 indicating the presence of depressive symptoms. Logistic regression models will be used to estimate odds ratios for depression across the four PA\_DQ groups, using the Inactive\_Unqualified group as the reference.Odds Ratio (95% Confidence Interval)

Subgroup analysis for All-Cause Mortality by Combined Physical Activity and Diet Quality Categories in Adults With Diabetes and Comorbid Depression

All-cause mortality will be determined from the NHANES Linked Mortality Files, which are linked to the National Death Index (NDI). Participants will be classified into four combined PA\_DQ categories: Inactive\_Unqualified (PA \<600 MET-min/week and HEI-2015 \<60) Inactive\_Qualified (PA \<600 MET-min/week and HEI-2015 ≥60) Active\_Unqualified (PA ≥600 MET-min/week and HEI-2015 \<60) Active\_Qualified (PA ≥600 MET-min/week and HEI-2015 ≥60) Subgroup analyses will examine whether hazard ratios for all-cause mortality associated with these PA\_DQ categories differ across age (\<65 vs ≥65 years), sex, BMI (\<29 vs ≥29 kg/m²), and sedentary time (\<4 vs ≥4 hours/day). Cox proportional hazards models with interaction terms will be used, and results will be reported as stratified hazard ratios relative to the Inactive\_Unqualified group.

Time frame: From baseline NHANES examination to December 31, 2019 (up to 120 months follow-up)