The Effects of Thiazolidinedione on the Diabetic Retinopathy and Nephropathy

Objectives:

Thiazolidinediones (TZDs) are insulin sensitizers that decrease plasma glucose in type 2 diabetic patients. Thiazolidinediones can cause fluid retention and peripheral edema in diabetic patients, and the systematic fluid retention can be manifested as diabetic macular edema (DME). The overall goal of this study is to examine the effects of thiazolidinediones on the diabetic retinopathy and nephropathy.

Study design:

This is a prospective, randomized, open-labeled, controlled design to assess the effects thiozolidinediones on the diabetic retinopathy and nephropathy. The investigators will recruit 300 type 2 diabetic patients without significant retinopathy, nephropathy and cardiovascular disease. Inclusion criteria are type 2 diabetes, age between 30-80 years old, with microabluminuria, no significant retinopathy, on submaximal dose of sulphonylureas and metformin treatment, and A1C between 7-9%. Exclusion criteria are on insulin treatment, significant retinopathy and significant nephropathy. Patients with cardiovascular diseases, malignancy, pregnancy, in acute intercurrent illness, congestive heart failure, myocardial infarction, received PCI or CABG. All subjects will receive EKG and CXR before randomization.

These subjects will be randomized equally to 3 groups: acarbose, rosiglitazone and pioglitazone. The investigators will follow up for 6 months to investigate the short-term effects and 5 years to evaluate the long-term outcomes. The primary study end point of short-term study will be the macular thickness changes measured by optical coherence tomography, the changes in the level of urinary albumin-to-creatinine ratio, circulating metabolic parameters and adipocytokines during thiozolidinediones treatment. Secondary end point will be fasting blood glucose, A1C levels, development of clinically significant macular edema, serum creatinine change in patients with no history of diabetic retinopathy and nephropathy at baseline.

The primary study end point of long-term study will be the development of clinically significant macular edema and the time from the base-line visit to the first detection of overt nephropathy. Secondary end points include the development of greater than moderate NPDR, the time to the first event of the time from the base-line visit to a doubling of the serum creatinine concentration, end-stage renal disease, or death.