Can Ruboxistaurin Help People With Diabetic Kidney Disease?

---

The effect of ruboxistaurin on nephropathy in type 2 diabetes, by K.R. Tuttle and colleagues. Diabetes Care 28:2686-2690, 2005.

What is the problem and what is known about it so far?

Nephropathy, or kidney disease, develops in approximately 40% of people with type 2 diabetes. It is the leading cause of death by kidney failure.

Why did the researchers do this particular study?

In studies on animals with kidney disease and diabetes, the drug ruboxistaurin has been shown to help improve kidney function. The researchers wanted to see if ruboxistaurin can help people with diabetes and kidney disease.

Who was studied?

A total of 123 patients with type 2 diabetes and chronic albuminuria, despite taking drugs to treat albuminuria. Albuminuria is when the there is a higher-than-normal amount of the protein albumin in the urine. Chronic albuminuria is a sign of kidney disease.

How was the study done?

In addition to their regular medications, 61 patients were given ruboxistaurin once a day for one year, and 62 were given a placebo (a pill that has no effect). Every few months, the researchers measured the patients' blood glucose levels; blood pressure; glomerular filtration rate, a measure of kidney health and function; and albumin-to-creatinine ratio, a measure of how well the kidneys are filtering out wastes.

What did the researchers find?

After one year, the amount of the protein albumin in the urine was lowered in the patients who took ruboxistaurin; this effect was seen after one month. The amount of albumin is the urine didn't change much in the patients who took the placebo. This shows that ruboxistaurin helped treat chronic albuminuria, a sign of kidney disease.

The glomerular filtration rate (or the kidneys' ability to filter out wastes) stayed the same in patients who took ruboxistaurin; it continued to worsen in those who took a placebo.

What were the limitations of the study?

The researchers weren't able to fully analyze the differences in kidney function between the two groups.

The patients weren't taking the same drugs or doses to treat albuminuria before or during the study.

Changes in lifestyle or medications could have had an effect on the study results.

The study was pretty small, so the researchers weren't able to make firm conclusions about the side effects of the drug.

What are the implications of the study?

Ruboxistaurin may help patients with type 2 diabetes who are taking medications to treat kidney damage. Larger studies are needed to see how safe and effective it is over long periods.

FOR MORE INFORMATION

Kidney Disease (Nephropathy)

American Diabetes Association Position Statement: Nephropathy in Diabetes, Clinical Practice Recommendations.

Uncomplicated Guide to Diabetes Complications, 2nd ed., Marvin E. Levin and Michael A. Pfeifer, Eds