Dr. Angela Ryan Lee is board certified in cardiology and internal medicine. Her professional interests include preventive cardiology, medical journalism, and health policy.
Anisha Shah, MD, is a board-certified internist, interventional cardiologist, and a fellow of the American College of Cardiology.
Low blood pressure (hypotension) is marked by symptoms of dizziness and fatigue and can have many causes. While many people with diabetes have high blood pressure, diabetes can also cause low pressure from dehydration, damage to the autonomic nervous system, or medication side effects.
This article will explore whether low blood pressure can be a symptom of diabetes, and the potential causes and treatment options for low blood pressure.
Adam Berry / Stringer
Normal blood pressure for adults is less than 120/80 millimeters of mercury (mm Hg). There is no specific numeric cutoff for "low" blood pressure. Rather, symptoms of low blood pressure are markers of a problem. These include:
Low blood pressure has many causes, including:
More often, people with diabetes have high blood pressure. However, diabetes can also cause low blood pressure due to:
When blood sugar is very high, as occurs in untreated diabetes, it causes sugar to leak into the urine. The sugar in the urine also drags water with it, which can result in dehydration. When significant, dehydration results in low blood pressure.
A serious condition called diabetic ketoacidosis (DKA) leads to significant dehydration with high levels of sugar in the blood and urine. Symptoms of DKA include fatigue, abdominal pain, nausea, frequent urination, and dry mouth. DKA is sometimes the first sign of type 1 diabetes in someone who has not been diagnosed.
Hyperosmolar hypoglycemic state is a similar condition that occurs more often in people with type 2 diabetes. It causes severe dehydration.
People with longstanding diabetes can develop damage to the nerves from chronically high blood sugar levels. This can result in autonomic neuropathy, a condition that can cause episodes of low blood pressure. Low blood pressure can occur with standing (orthostatic hypotension) or after eating (postprandial hypotension) and cause symptoms like dizziness, lightheadedness, and even falls.
In autonomic neuropathy, damaged nerves don't appropriately transmit signals to blood vessels to constrict to appropriately maintain blood pressure levels. This can lead to abrupt drops in blood pressure, particularly when standing.
Some medications used to treat diabetes can have low blood pressure as a side effect. Sodium-glucose cotransporter 2 (SGLT2) inhibitors work by increasing the amount of blood sugar lost in the urine, which can contribute to low blood pressure. Examples of SGLT-2 inhibitors include:
If you take any of these medications, talk with your healthcare provider about possible side effects.
Determining the cause of low blood pressure is the first step in managing it. For example, if the cause is dehydration from excess fluid losses, getting better control of your blood sugar and staying well-hydrated can help.
For people who get low blood pressure after a meal (post-prandial hypotension) or after sitting or standing (orthostatic hypotension), the following may help:
If you feel faint or experience dizziness, it's always safest to sit or lie down. This will help to avoid injury in the event of falls or fainting. In autonomic neuropathy, other treatments might be required, such as medications that can help raise blood pressure (e.g, midodrine and fludrocortisone).
If you have signs of low blood pressure make an appointment with your healthcare provider to find out what is causing it. Low blood pressure can be dangerous. You should seek emergency medical attention if you experience the following symptoms:
Diabetes is more often linked with high blood pressure, but it can also cause low blood pressure. There's no cutoff number for blood pressure to be considered low; rather, low blood pressure is of concern when it causes symptoms. Diabetes can be linked to low blood pressure that's caused by dehydration, autonomic neuropathy, and medication side effects. Talk with your healthcare provider about any symptoms you have. They can find out the cause and come up with a treatment plan for you.
Episodes of low blood pressure can be frightening and affect your daily life. If you find yourself with frequent episodes of dizziness and vision changes that are linked to low blood pressure, talk to your provider about steps you can take to minimize your symptoms and keep your blood pressure at a normal level.
Normal blood pressure is considered less than 120/80. Blood pressures lower than this can still be normal, and there's no numeric cutoff for low blood pressure. Rather, it's the symptoms of low blood pressure that can make it a concern. For example, low blood pressure can cause lightheadedness, vision changes, and fainting.
While diabetes is more often associated with high blood pressure, it can be linked to low blood pressure, too. Diabetic autonomic neuropathy can cause low blood pressure, particularly with standing or after meals due to damage to the autonomic nervous system. Additionally, dehydration can occur in diabetes when blood sugar is elevated, and this can be an early indicator of diabetes in people who have not been diagnosed.
There are several different classes of medication used to treat diabetes. One class that is known for lowering blood pressure and potentially causing dehydration is SGLT-2 inhibitors. These medications work by increasing the amount of sugar lost in the urine, which also leads to fluid loss. Dehydration and low blood pressure can be side effects.
American Heart Association. Low blood pressure- when blood pressure is too low.
National Library of Medicine, Medline Plus. Diabetic ketoacidosis.
Endocrine Society. Hyperglycemia.
Centers for Disease Control and Prevention. Diabetes and nerve damage.
National Library of Medicine, MedlinePlus. Autonomic neuropathy.
Food and Drug Administration. Sodium-glucose cotransporter-2 inhibitors.
National Institute of Diabetes and Digestive and Kidney Diseases. Autonomic neuropathy.
National Organization for Rare Disorders. Orthostatic hypotension.
Mar PL, Raj SR. Orthostatic hypotension for the cardiologist. Curr Opin Cardiol. 2018 Jan;33(1):66-72. doi:10.1097/HCO.0000000000000467
Mount Sinai. Low blood pressure.
Angela Ryan Lee, MD, is board-certified in cardiovascular diseases and internal medicine. She is a fellow of the American College of Cardiology and holds board certifications from the American Society of Nuclear Cardiology and the National Board of Echocardiography. She completed undergraduate studies at the University of Virginia with a B.S. in Biology, medical school at Jefferson Medical College, and internal medicine residency and cardiovascular diseases fellowship at the George Washington University Hospital. Her professional interests include preventive cardiology, medical journalism, and health policy.
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