. Author manuscript; available in PMC: 2021 Jan 1.

Published in final edited form as: Mov Disord. 2019 Sep 4;35(1):55–74. doi: 10.1002/mds.27836

Table 1a:

Diabetes (Cohort studies)

Author (Year)	Source population	Country	Sample size	Definition of Diabetes & PD, covariates	Results	Adjusted variables	Remarks
De Pablo-Fernandez et al. 2018³⁷	Hospital-based cohort of Type 2 DM patients and diabetes-free controls	UK	14’252 PD patients	PD: 1^st hospital admission for PD Exclusion of individuals with a coded diagnosis of cerebrovascular disease, vascular/drug-induced parkinsonism, or normal pressure hydrocephalus DM: Hospital admission for type 2 DM	Overall: HR 1.32 (95% CI 1.29–1.35) Patients aged 25–44 y at the time of the 1^st admission for DM: 3.81 (95% CI 2.84–5.11), result based on small numbers (58 PD patients) Women: 1.42 (95% CI 1.37–1.47) Men: 1.27 (95% CI 1.23–1.30)	Age, sex, year of cohort entry, region of residence, socioeconomic status	Sensitivity analyses: exclusion of patients with <1 yr between DM and PD: same results Limitations: Potential selection bias caused by restriction to hospitalized cases (i.e., more severe DM)
Yang et al. 2017¹⁵⁹	National Health Insurance claims database Mean follow-up 7.3 y	Taiwan	1’782 PD patients	PD: ≥3 Dx in ambulatory care or ≥1 Dx in inpatient care DM: Same as for PD, Dx based on ADA criteria	Overall : HR 1.19 (95% CI 1.08–1.32) Women 1.29 (95% CI 1.12–1.49) Men : 1.12 95% CI (0.97–1.30)	Age, sex, insurance premium, residential area, occupation, CCI, schizophrenia and bipolar disorder, prescription of flunarizine, MCP or zolpidem	Exclusion of patients with <1 yr between DM and PD
Sun et al. 2012¹⁶⁰	National Health Insurance claims database	Taiwan	2’422 PD patients	PD: Outpatient claims or hospitalization records (≥1 year after cohort entry) DM: Prevalent Dx plus ≥1 DM Dx during follow-up	Overall: HR 1.61 (95% CI 1.56–1.66) Women : HR 1.70 (95% CI 1.63–1.77) Men: HR 1.51 (95% CI 1.44–1.57) Men (21–40 y): HR 2.10 (95% CI 1.01–4.42) Additional adjustment for medical visits : Overall HR 1.37 (95% CI 1.32–1.41)	Age, sex, geographic area, urbanization status, medical visits, hypertension, hyperlipidemia, cardiovascular disease	Results for men (21–40 ys) based on 6 PD cases
Xu et al. 2011³⁸	National Institutes of Health-AARP Diet and Health Study	USA	1’565 PD patients	PD: Self-reported, validated by the treating physician DM: Self-reported	OR 1.41 (95% CI 1.20–1.66) Only patients with DM duration at baseline ≥10 y: OR 1.75 (95% CI 1.36–2.25)	Age, sex, race, education, smoking, coffee consumption, BMI, physical activity	Sensitivity analysis: exclusion of cases with stroke, heart disease, cancer, or poor/fair health: similar results
Palacios et al. 2011¹¹⁴	Cancer Prevention Study II Nutrition Cohort Mean follow-up 6.4 y	USA	656 PD patients	PD: Incident, confirmed by neurologist or medical record review DM: Self-reported at baseline	HR 0.88 (95% CI 0.62–1.25)	Age, sex, smoking, diet, alcohol/coffee consumption, BMI, education, physical activity, pesticide exposure	Sensitivity analyses: exclusion of PD cases during first 5 y of follow-up: similar results
Driver et al. 2008³⁶	Physicians Health Study (randomized trial) Median follow-up 23.1 y	USA	556 PD patients	PD: Self–reported (90% accurate according to validation study) DM: Self–reported (Type 2 DM)	Men: RR 1.34 (95% CI 1.01–1.77) Association significantly modified by BMI (increased risk of PD with low BMI)	Age, smoking, alcohol consumption, BMI, hypercholesterolemia, hypertension, physical activity	Increased risk with shorter DM duration -> no causal association
Simon et al. 2007⁴⁰	Nurses’ Health Study and Health Professionals Follow-up Study Mean Follow-up: 22.9 y/12.6 y	USA	530 PD patients	PD: Self-report, confirmed by treating physician (15%), neurologist (82%), or by review of medical records (3%) DM: Self-reported physician’s Dx (validated) PD and DM status assessed at baseline and every 2 ys thereafter	With updated history of DM: RR 1.04 (95% CI 0.74–1.46) Only baseline info on DM: RR 1.12 (95% CI 0.69–1.81)	Age, sex, smoking	Patients with prevalent stroke excluded Additional adjustment for BMI, physical activity, hypertension, cholesterolemia, alcohol/coffee consumption, diet, NSAID use yielded similar results
Hu et al. 2007¹⁶¹	Prospective study based on cross-sectional surveys in five geographic areas Mean follow-up 18 y	Finland	633 PD patients	PD: Data from the National Insurance Institution register, confirmed by two neurologists DM: Self-report, hospital discharge diagnoses or drug claims Assessment of covariates by questionnaires	Overall: HR 1.85 (95% CI 1.23–2.80) Men: HR 1. 08 (95% CI 1.03–3.15) Women: HR 1.93 (95% CI 1.05–3.53)	Age, study year Additional adjustments for BMI, systolic blood pressure, cholesterol, education, physical activity smoking, alcohol/coffee/tea consumption yielded similar results	Only baseline info on DM included Similar results in several sensitivity analyses
Grandinetti et al. 1994³⁹	Honolulu Heart Program Follow-up: 26 ys	USA	58 PD patients	PD: Hospital records, death certificates, or medical records of neurologists DM: Self-report plus physical examination at baseline	RR 1.20 (95% CI 0.67–2.12)	Age	Main objective of the study: assessment of the impact of cigarette smoking on the risk of PD

AARP = American Association of Retired Persons; ADA = American Diabetes Association; BMI = Body mass index; CCI = Charlson Comorbidity Index; CI = Confidence interval; DM = Diabetes mellitus; Dx = Diagnosis, HR = Hazard ratio; NSAID: Non-steroidal anti-inflammatory drugs; MCP = metoclopramide; OR = Odds ratio; PD = Parkinson disease; RR = Relative risk; Rx = Prescription; UK = United Kingdom; yr/ys = year(s)