Diabetes Mellitus in California: Complications, Modifiers and Spatial Determinants

Diabetes mellitus (DM) is a metabolic disease whose prevalence has steadily risen in the United States and globally over the last three decades. In addition to its direct effects on hyperglycemia, DM has a variety of associated complications, ranging from an increased risk of cardiovascular disease to an increased risk for multiple infectious diseases. Because of these complications, DM remains a major source of disease burden in the United States and globally. Even as the prevalence of DM has risen, so too have awareness of the disease and the armamentarium of medications available for its treatment. These changes in both awareness and the ability to treat the disease have ostensibly had an impact. Rates of some of the most important complications of DM, including cerebrovascular accident (CVA) and myocardial infarction (MI) have declined in the United States while at the same time, the prevalence of DM has leveled off. In this dissertation, I focus on three separate, but linked issues about DM. All of the work I present here was done either at the state level in California or at the level of the city of San Francisco. In chapter 1, I examine whether the decreases that have been observed for non-infectious complications of DM are also true for its infectious complications in California overall. In chapter 2, in a cohort of patients in San Francisco, I examine the potential role of medications that are frequently used to treat other conditions in persons with DM in driving the increased risk of infection in persons with DM as well as the findings I describe in chapter 1. Finally, in chapter 3, working with the same cohort studied in chapter 2, I examine the role of distance to the primary care clinic, a potentially modifiable factor, in determining diabetes control.In chapter 1 of this dissertation, I show that in California, rates of hospitalization for infectious diseases among persons with DM have steadily increased. This result contrasts both with what has been reported for non-infectious disease complications of DM nationally as well as with my own findings for two important non-infectious disease complications of DM, CVA and MI. My results suggest that other factors beyond the level of control of DM could drive the risk of infection among persons with DM. In chapter 2, I show that while one such potential factor, collateral effects of medications used to treat other conditions (e.g. hyperlipidemia,hypertension) in persons with DM, does not appear to drive the increase risk of infection in persons with DM, two medication classes, angiotensin converting enzyme inhibitors (ACEI) and angiotensin receptor blockers (ARB) could actually reduce the risk of developing in infection. Finally, in chapter 3, I show that minimizing the distance between patients and their primary care clinics has the potential to result in a significant improvement in control of DM, as measured by the glycated hemoglobin level. Together, the three chapters of this dissertation provide a comprehensive view of DM in California as a whole and in San Francisco in particular. My findings shed new light on one of DM’s most important complications, infectious diseases, while at the same suggesting two potential methods to limit the development of these and potentially other DM-related complications