Hypertension, or high blood pressure, often occurs alongside diabetes mellitus, including type 1, type 2, and gestational diabetes, and studies show there may be links between them.
Both hypertension and diabetes may have some underlying causes in common, and they share some risk factors. They also contribute to a worsening of each other's symptoms. The ways of managing both conditions also overlap.
Read on to find out more about the link between high blood pressure and diabetes, how to detect them, and how to reduce the negative impact of both.
Some relatively simple tests can show if a person has diabetes or hypertension.
People can also buy blood glucose testing kits for diabetes and blood pressure monitors for blood pressure, which they can use at home.
People sometimes refer to hypertension as the "silent killer," and many people are not aware they have it.
The American Heart Association (AHA) stress that most of the time there are no symptoms.
People usually find out they have high blood pressure when a doctor takes a blood pressure reading, or they take one themselves at home.
The reading will give two numbers:
- The systolic is the top number
- The diastolic is the bottom number
According to the AHA, the results will be one of the following:
- Normal: Systolic below 120 and diastolic below 80
- Elevated: Systolic 120–129 and diastolic under 80
- Hypertension stage 1: Systolic 130–139 and diastolic 80–89
- Hypertension stage 2: Systolic 140-plus and diastolic 90 or more
- Hypertensive crisis: Systolic higher than 180 and diastolic above 120.
A hypertensive crisis means that the individual needs to see a doctor immediately.
A person with early-stage hypertension has a risk of developing hypertension in the future.
Lifestyle habits can help control blood pressure and prevent hypertension and its complications. These lifestyle influencers include:
- a healthful diet
- weight control
Not everyone with diabetes will notice symptoms, including those with a diagnosis, as long as they are controlling their condition effectively.
If symptoms of high blood sugar levels do appear, they include:
- excessive thirst
- frequent need to urinate
- increased night time urination
- weakness and tiredness
- blurred vision
A person may also notice that they start to have more infections, including urinary tract infections, thrush, and upper respiratory tract infections. They may also notice that wounds and infections take longer to heal.
Tests will show that a person has high levels of sugar in their urine and blood.
Glucose levels after fasting for 8 hours may be:
- Normal: Less than 100 milligrams per deciliter (mg/dl)
- Prediabetes: Between 100–125 mg/dl
- Diabetes: A reading of 126 mg/dl or above
Other tests that a doctor may carry out will show the results in different ways.
There are three kinds of diabetes mellitus, all of which have different causes:
Type 1 diabetes tends to appear during childhood or adolescence, but it can occur later in life. Symptoms can emerge relatively suddenly or over a number of weeks. Type 1 happens when the immune system attacks the cells in the pancreas that produce insulin. There is no way to avoid type 1 diabetes.
Type 2 diabetes can take years to develop, and most people do not notice symptoms. Someone typically finds out that they have prediabetes or type 2 diabetes when they attend a screening or if complications occur, such as neuropathy or kidney problems.
Current guidelines recommend screening for everyone over the age of 45 years or before if they have risk factors, such as obesity.
This precaution is because someone with an early diagnosis has a better chance of reversing or slowing the progress of the condition and avoiding complications before they start.
One way to do this is through similar lifestyle choices that doctors recommend for hypertension.
Click here to find out more about type 1 and type 2 diabetes.
Gestational diabetes occurs only in pregnancy, but it can increase the risk of type 2 diabetes later in life.
If the routine screening shows high blood sugar levels during pregnancy, a doctor will monitor the person's condition until delivery. They will continue to do this for a few weeks afterward, but blood sugar levels usually fall.
Gestational diabetes can lead to various complications, including pre-eclampsia, the main symptom of which is very high blood pressure.
Learn more here about gestational diabetes.
The authors of a 2012 study note that diabetes and hypertension often occur together and may share some common causes.
Can diabetes cause hypertension?
A person with diabetes either does not have enough insulin to process glucose or their insulin does not work effectively. Insulin is the hormone that enables the body to process glucose from food and use it as energy.
As a result of insulin problems, glucose cannot enter the cells to provide energy, and it accumulates in the bloodstream instead.
As blood with high glucose levels travels through the body, it can cause widespread damage, including to the blood vessels and kidneys. These organs play a key role in maintaining healthy blood pressure. If they experience damage, blood pressure can rise, increasing the risk of further harm and complications.
Can hypertension cause diabetes?
A meta-analysis appearing in the Journal of the American College of Cardiology (JACC) in 2015 looked at data for more than 4 million adults. It concluded that people with high blood pressure have a higher risk of developing type 2 diabetes.
This link may be due to processes in the body that affect both conditions, for example, inflammation.
The combined impact of diabetes and high blood pressure can increase the risk of cardiovascular disease, kidney disease, and other health problems.
In 2012, researchers quoted figures suggesting that 30% of people with type 1 diabetes and 50–80% of those with type 2 diabetes have high blood pressure in the United States.
There are three ways in which high glucose levels in the blood can increase blood pressure:
- The blood vessels lose their ability to stretch.
- The fluid in the body increases, especially if diabetes is already affecting the kidneys.
- Insulin resistance may involve processes that increase the risk of hypertension.
Controlling blood sugar levels and blood pressure can help prevent complications.
Hypertension and type 2 diabetes also share similar risk factors. These include:
- having excess weight and body fat
- following an unhealthful diet
- having an inactive lifestyle
- stress and poor sleep habits
- smoking tobacco
- older age
- having low levels of vitamin D
Having a family history of hypertension increases the risk of hypertension, while a family history of diabetes increases the risk of diabetes, particularly type 2.
Having hypertension appears to increase the risk of type 2 diabetes, and having type 2 diabetes increases the risk of hypertension.
Also, having one or both conditions increase the risk of various complications, including:
- heart attack or stroke
- decreased kidney function, progressing to dialysis
- problems with the blood vessels in the eyes, leading to vision loss
- peripheral vascular disease
Other factors that increase the risk of hypertension include:
- having a high fat or high sodium diet
- high alcohol consumption
- low levels of potassium
- other chronic conditions, such as sleep apnea, kidney disease, or inflammatory arthritis
Making healthful lifestyle choices from an early age can help prevent both type 2 diabetes and hypertension. People with diabetes can help decrease the risk of high blood pressure and cardiovascular disease by controlling their blood sugar levels.
Lifestyle factors are crucial for managing both blood glucose and blood pressure.
A healthy weight
For people with excess weight, losing even a little can help reduce the risk of both high blood pressure and diabetes.
For people with excess weight, the National Heart, Lung, and Blood Institute (NHLBI) point out that if a person loses 3–5% of their weight, it can improve their blood pressure readings.
Similarly, the Centers for Disease Control and Prevention (CDC) note that losing 5–7% of body weight can help stop prediabetes from becoming diabetes. That would be a loss of 10–14 pounds for a person who weighs 200 pounds.
Regular activity can lower blood pressure and help control blood sugar, and it offers many other health benefits.
Current guidelines encourage everyone to do at least 150 minutes of moderate intensity aerobic exercise each week, or 75 minutes of vigorous intensity exercise. Moderate exercise includes walking and swimming.
Those who have not been active for a while should speak to their doctor for advice on a sensible exercise plan.
Healthful dietary choices
People with diabetes and hypertension should talk to their doctor about a dietary plan.
This will usually include:
- eating plenty of fresh fruits and vegetables
- focusing on high-fiber foods, including whole grains
- limiting the amount of added salt and sugar
- avoiding or limiting unhealthful fats, such as trans fats and animal fats
Doctors often recommend the DASH diet for managing blood sugar and overall wellbeing.
Learn more here about what to eat on the DASH diet.
A person with diabetes will need to monitor their intake of carbohydrates and check their blood glucose levels to ensure they meet the targets that their treatment plan sets out.
Limiting alcohol consumption
High consumption of alcohol can increase the risk of:
- raised blood pressure
- blood glucose spikes
- weight gain
The American Diabetes Association (ADA) recommend a maximum of one alcoholic drink per day for women and two alcoholic drinks per day for men.
One drink would be one 12-ounce beer, one 5-ounce glass of wine, or one 1.5-ounce serving of spirits, such as whiskey, gin, or vodka.
Mixers can also add carbohydrates and calories. Sparkling water is a more healthful option than sweetened soda.
An individual may wish to speak to their doctor about how much alcohol is safe for them to consume.
There is evidence that tobacco smoking can increase the risk of both high blood pressure and diabetes.
Smokers with diabetes have a higher risk of serious complications, including:
- heart or kidney disease
- retinopathy, an eye disease that may lead to blindness
- poor blood flow, making infection and the risk of amputation more likely in the legs and feet
- peripheral neuropathy, which can cause nerve pain in the arms and legs
A person who has or is at risk of diabetes, high blood pressure, or both can speak to their doctor about how to quit smoking.
Treatment with medication
In addition to lifestyle measures, a doctor may prescribe medications as follows:
Type 1 diabetes: The person will need insulin and possibly blood pressure and other medications, depending on any complications they have.
Type 2 diabetes: Some people will need to use insulin, or a doctor may prescribe metformin or other non-insulin medications to help reduce blood sugar levels. They may also need medications for high blood pressure or other complications.
Current guidelines also recommend using one of the following if a person with type 2 diabetes has a high risk of atherosclerotic cardiovascular disease, diabetes-related kidney disease, or both.
- sodium-glucose cotransporter 2 inhibitors (SGLT2)
- glucagon-like peptide 1 (GLP-1) receptor agonists
These drugs offer protection to the heart and kidneys by helping control blood sugar levels.
Hypertension and diabetes often occur together, and they appear to share some risk factors and causes.
Lifestyle adjustments can help control blood pressure and blood sugar levels, but most people will need to follow a treatment plan for life.
A doctor will prepare a treatment plan with the individual, who must stay in touch with their healthcare team and check in with a healthcare professional if they believe they need to adjust their treatment.