This study examined the relationship between type 2 diabetes and Parkinson's disease in a cohort of over 21,000 US male physicians over 23 years: 1) Men with a history of type 2 diabetes had a 34% increased risk of Parkinson's disease compared to non-diabetic men. 2) The highest risk was seen in those with short-duration, older-onset diabetes without complications. 3) Differences in diabetes incidence between Parkinson's patients and controls were greatest near the time of Parkinson's diagnosis, suggesting detection bias rather than a causal relationship.

1. SUSHIL SRIVASTAVA

11. Prospective Cohort Study of Type 2 Diabetes and the Risk of Parkinson's Disease SUSHIL SRIVASTAVA

17. RR’ of Parkinson’s according to history of type 2 diabetes No DIAB DIAB RR RR in DIAB p value Participants 19431 2410 1 1.34 <55 yrs 11684 1247 1 1.12 0.81 55--64 5140 790 1 1.57 > 65 2607 373 1 1.25 BMI < 25 11720 858 1 1.88 0.04 25-- <30 7097 1247 1 1.14 >30 614 305 1 0.36

18. RR’ of Parkinson’s according to history of type 2 diabetes No DIAB DIAB RR RR in DIAB p value Diab. complication 19431 No 1475 1 1.63 .0002 Yes 935 1 1.10 Diab. duration 19432 <5 562 1 7.17 <.0001 5—9 631 1 2.03 10—14 482 1 0.82 >15 734 1 0.73

19. RR’ of Parkinson’s according to history of type 2 diabetes No DIAB. DIAB RR RR in DIAB P value Age at onset of diabetes < 63.7 1213 1 1.18 <o.ooo2 > 63.7 1197 1 1.49