High Blood Sugar Levels Contribute to High Blood Pressure By Paula Rasich Reviewed by Elizabeth Klodas, MD, FACC October 7, 2008--Up to 70% of people with diabetes have hypertension (high blood pressure). Now, new research suggests that blood sugar (glucose) levels that aren’t well regulated could be the reason.

Examining data from a two-part long term follow up study of diabetics, a team of scientists led by Ian H. de Boer, MD, MS, of the University of Washington, investigated the effects of intensive insulin therapy (multiple daily shots or use of an insulin pump) and blood sugar control on high blood pressure. Previous research has shown that frequent insulin injections, which improve blood sugar significantly, lower the risk of kidney, eye and other diabetes-related complications.

In the trial 1,441 type 1 (insulin requiring) diabetics, 13 to 39 years of age, were randomized to receive either intensive or conventional insulin therapy (up to two daily shots) for six and half years. Of those, 1,375 were tracked for an additional 12 years as part of a longer follow up study. Blood pressure readings and HbA1c measurements (3-month blood sugar averages) were recorded regularly throughout the trial.  Normal HbA1c levels are considered below 6%; in diabetics the goal is to keep HbA1c levels below 7%.

Over the course of about 16 years, 630 participants developed high blood pressure. Researchers found that those who received intensive therapy were 24% less likely to develop high blood pressure than those receiving conventional therapy.  In addition, when researchers used the full history of HbA1c measurements to summarize blood sugar control for each person, they found that each 1% HbA1c increase was associated with a 25% greater risk of hypertension. 

“This study offers a very powerful argument that glucose itself is somehow involved in the [development] of hypertension in type 1 diabetes. [High blood sugars] may lead to arterial stiffness over the long term,” says Dr. de Boer. “And this study identifies for the first time that prevention of high blood pressure is an additional benefit of intensive diabetes [insulin] therapy.”

The study participants were mostly white, so the results may not apply to the larger population. The findings are published in the September 22nd issue of the Archives of Internal Medicine.

Sources:

de Boer IH et al. Insulin Therapy, Hyperglycemia, and Hypertension in Type 1 Diabetes Mellitus. Archives of Internal Medicine: September 22, 2008.

Ian H. de Boer, MD, MS, Assistant Professor of Medicine, Division of Nephrology, University of Washington, Seattle, Washington.