A Pilot Study of Moderate Hyperbilirubinemia in Type 1 Diabetes Mellitus

Diabetes mellitus (DM) is associated with a markedly increased risk of both macro- and
microvascular disease. Excess pro-oxidants and insufficient antioxidants each contributes to
oxidant stress in DM. Oxidant stress induces endothelial dysfunction, a major determinant of
vascular damage. In DM, hyperglycemia and elevated free fatty acids (FFAs) induce generation
of reactive oxygen species (ROS) by stimulating protein kinase C (PKC) and nicotinamide
adenine dinucleotide phosphate (NADPH) oxidase (Figure 1). In addition, hyperglycemia
activates the renin-angiotensin system, and angiotensin II (Ang II) additively stimulates
PKC and NADPH oxidase.

Bilirubin, long regarded as metabolic waste, is, in fact, a potent antioxidant scavenger of
ROS. It also directly inhibits both protein kinase C and the NADPH oxidase system,
augmenting its antioxidant activity (Figure 1). Moreover, bilirubin inhibits Ang II-mediated
vasoconstriction and ROS generation. Experimental models suggest that hyperbilirubinemia may
preserve diabetes-associated endothelial function and prevent vasculopathy. Furthermore,
epidemiological studies demonstrate that higher bilirubin levels are associated with a
reduced risk of vascular disease in DM. Bilirubin therefore emerges as a potentially
critical molecule to protect against diabetic vascular and renal damage. However, limited
translational research has addressed raising bilirubin levels as a preventive therapy for
vascular disease in DM.

Accordingly, the investigators seek to establish the feasibility of studying the change in
endothelial function caused by induced moderate hyperbilirubinemia in type 1 diabetes. the
investigators will take advantage of the recently described use of atazanavir to safely
achieve moderate hyperbilirubinemia. Atazanavir is a protease inhibitor used to treat HIV
infection that competitively inhibits hepatic 1A1 isoform of uridine diphosphoglucose
glucuronosyltransferase (UGT1A1), limiting bilirubin clearance and inducing
hyperbilirubinemia (Figure 2). This mimics Gilbert's syndrome, a benign unconjugated
hyperbilirubinemia due to partial genetic deficiency of UGT1A1.

This work has the potential to identify iatrogenic moderate hyperbilirubinemia as a strategy
to interrupt key mechanisms of type 1 diabetes-associated macro- and microvascular disease.

This is a physiologic study. The design is a single arm and open label. There are three
study visits: a screening visit, a baseline visit, and a final visit. The treatment is
atazanavir 300 mg PO bid. The treatment period is 4 days. The primary study outcome is
forearm vascular function. The principal secondary outcomes are serum antioxidant defense
capacity and measures of oxidant stress.

The investigators aim to study 20 subjects to completion over the 12 month funding period.
The investigators anticipate enrolling 40 subjects before 20 complete the study.

Inclusion Criteria:

1. Symptoms of diabetes plus casual plasma glucose concentration ≥ 200 mg/dl (11.1
mmol/l), or;

2. FPG ≥ 126 mg/dl (7.0 mmol/l), or;

3. 2-h postload glucose ≥ 200 mg/dl (11.1 mmol/l) during an OGTT. In addition, subjects
would be required to be at increased risk of cardiovascular events, defined as:

- microalbuminuria, or;

- T1DM duration of > 20 years.

Exclusion Criteria:

1. HIV infection

2. Gilbert's syndrome

3. Hepatic failure or active hepatitis,

4. Unstable cardiovascular disease, including angina, heart failure or arrhythmia

5. drug abuse including alcoholism or addiction to cocaine, heroin or amphetamines

6. Use of medications that significantly with atazanavir

7. Pregnancy, or inability to practice adequate contraception