Table 1a:
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: 1st 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 1st 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)