Diabetes therapy often includes medication to lower blood pressure. Current analyses of clinical studies suggest that blood pressure should not only be controlled from above but also from below. The German Diabetes Association (DDG) and diabetesDE emphasize that blood pressure in patients with diabetes should not be reduced excessively, because many diabetic patients suffer from narrowing of the coronary arteries. If blood pressure falls too far, the heart may no longer receive an adequate blood supply.
Both elevated blood glucose levels caused by diabetes and high blood pressure damage blood vessels over time. They significantly increase the risk of stroke and heart attack. Therefore, regular monitoring of blood pressure and treatment of hypertension are essential parts of diabetes management.
The DDG traditionally recommended a resting blood pressure target of no more than 130/80 mmHg. In healthy individuals, a blood pressure of approximately 120/80 mmHg is considered optimal. Slightly lower values are usually not harmful in healthy people. However, for patients with coronary artery disease — a condition frequently present in people with diabetes — a systolic blood pressure of 120 mmHg may already be too low in some cases.
Particularly, a diastolic blood pressure below 70–75 mmHg should generally be avoided in patients with coronary artery disease. The diastolic value represents blood pressure during the relaxation phase of the heart (diastole). During this phase, the heart muscle itself receives oxygen-rich blood through the coronary arteries. If diastolic blood pressure falls excessively, coronary blood flow may become insufficient.
Because many diabetic patients have narrowing of the coronary arteries, they require a certain “pressure reserve” to maintain adequate blood flow to the heart muscle. Otherwise, cardiovascular complications may occur. This concept is supported by analyses of several clinical studies and is commonly referred to as the “J-curve phenomenon,” meaning that both excessively high and excessively low blood pressure may increase cardiovascular risk.
One important study addressing this issue was the ACCORD trial. Nearly 5,000 patients with diabetes and hypertension participated in this study.
Although the lower target did not significantly reduce overall rates of death or myocardial infarction, it was associated with a reduction in stroke risk. However, more treatment-related side effects occurred in the intensive-treatment group.
These side effects included:
Other clinical studies have also suggested that excessively low blood pressure in patients with coronary artery disease may increase the risk of complications.
For this reason, the European Society of Hypertension (ESH) reevaluated its recommendations. Likewise, diabetesDE and the DDG recommend individualized blood pressure targets in patients with diabetes. In many patients, a target blood pressure below 130/80 mmHg is appropriate if treatment is well tolerated. However, excessively low diastolic blood pressure should be avoided, particularly in patients with coronary artery disease, advanced vascular disease, or older age.
Despite these considerations, persistently elevated blood pressure in patients with diabetes remains a major risk factor for cardiovascular disease, stroke, heart failure, kidney disease, and premature death.