Diabetes and high blood pressure commonly co-exist. In fact, a person with diabetes is twice as likely to have high blood pressure as someone who is diabetes free. Similarly, patients with high blood pressure are more resistant to insulin-stimulated glucose uptake than matched control groups with normal blood pressure.
Do these two medical conditions simply share common risk factors? Or is there a deeper relationship between blood pressure and blood sugar?
Blood Sugar Basics
When people eat foods, primarily carbohydrates, the digestive system breaks food down into sugar, which enters the blood. Blood sugar, or glucose, is the primary energy source for all cells in your body. Multiple hormones are in charge of regulating blood sugar levels on a regular basis. If blood sugar falls too low, known as hypoglycemia, the body will produce “gluco-counter-regulatory” hormones, including catecholamines.
These hormones, such as epinephrine, cortisol, growth hormone, and glucagon, act through different mechanisms to increase blood sugar levels. On the other hand, if blood sugar rises too high, referred to as hyperglycemia, the body produces insulin. This hormone drives sugar out of the bloodstream into the muscle, fat, and liver cells, ultimately decreasing blood sugar.
Sometimes the intricate system that controls blood sugar stops functioning effectively. Often, this leads to chronic hyperglycemia. Hyperglycemia, by definition, is blood glucose greater than 125 mg/dL while fasting or blood glucose greater than 180 mg/dL two hours after eating. Moreover, if fasting glucose ranges from 100-125 mg/dL, this is considered impaired fasting glucose and may indicate pre-diabetes. Early symptoms of hyperglycemia include increased thirst/hunger, blurred vision, rapid heart rate, frequent urination, and headache. Hyperglycemia over time can lead to symptoms like fatigue, weight loss, increased risk for infection, and slow healing capabilities.
Reasons for hyperglycemia can be acute, such as physical stress (illness or infection), emotional stress (dealing with a breakup or new job), or due to certain medications (steroids or diuretics). Hyperglycemia can also be caused by chronic conditions such as endocrine or pancreatic diseases like Cushing syndrome or long-term insulin resistance.
Insulin resistance occurs when insulin’s ability to stimulate glucose uptake by the tissues is impaired. Often when the body stops responding to insulin, the pancreas will have to produce higher amounts of insulin, termed hyperinsulinemia, to get the same results. Prolonged high blood sugar levels can damage blood vessels and nerves, lead to heart disease, and permanently damage the eyes or kidneys.
Blood Pressure Basics
Blood pressure is the force of blood pushing against your blood vessel walls. Maintaining a healthy blood pressure is important because it allows for adequate amounts of oxygen and nutrients to be pushed around the circulatory system and delivered to the body’s organs and tissues. But like blood sugar, blood pressure can fluctuate and is managed through several mechanisms by many of the same hormones that help manage blood sugar. Hormones that can increase blood pressure include adrenal hormones and catecholamines like aldosterone, cortisol, adrenaline, and insulin. Hormones and regulators that can decrease blood pressure include nitric oxide, natriuretic peptides, and vasodilator peptides.
Hypertension, or high blood pressure, is when the heart must use high force to pump blood through the heart and blood vessels. When measuring blood pressure, the first, or top, number is “systolic pressure,” which is the pressure in your arteries when your heart contracts. The second, or bottom, number is the “diastolic pressure,” which is the pressure in your arteries when your heart rests.
The American Heart Association (AHA) categorizes normal blood pressure as 120/80 or below. Hypertension usually has no signs or symptoms, which is why it’s often referred to as the “silent killer.” It’s estimated that half of Americans over the age of 20 have high blood pressure, and half of those don’t even know it. However, some may experience episodes of headache, dizziness, or blurred vision when blood pressure is significantly elevated.
Reasons for hypertension can vary. Primary hypertension may be caused by diverse reasons, including genetics, excessive salt intake, obesity, lack of exercise, or use of tobacco and alcohol. Secondary hypertension is due to particular medical conditions such as kidney disease, Cushing’s syndrome, or prescription medications. If untreated, hypertension can lead to life-threatening complications such as heart attack, heart failure, stroke, or kidney failure.
Can Blood Sugar Affect Blood Pressure?
Yes. It turns out that hyperglycemia can contribute to hypertension. High blood sugar can increase blood pressure through two primary means. First, untreated hyperglycemia can lead to nerve and blood vessel damage. Damage to the blood vessels causes the walls to stiffen, narrow, and accumulate plaque. Plaque buildup narrows the vessels, increasing pressure and contributing to hypertension.
Second, chronic hyperglycemia leads to chronic hyperinsulinemia. Hyperinsulinemia can increase blood pressure by (1) increasing renal sodium and water reabsorption, (2) activating the sympathetic nervous system, which increases heart rate and contracts the blood vessels, (3) altering transmembrane ion transport leading to intracellular accumulation of sodium and sensitizing the arteriolar smooth muscle to pressor hormones, and (4) increasing vascular resistance by leading to hypertrophy of the vascular walls and narrowing of the blood vessels. Therefore, it’s high insulin levels that lead to high blood pressure. But the best way to manage insulin levels is by managing blood sugar levels.
Finally, since the same hormones (catecholamines) are used for increasing blood sugar and increasing blood pressure, it’s important to note that hypoglycemia can also lead to high blood pressure. If blood sugar falls too low the body releases hormones like adrenaline to increase blood sugar back to normal levels. Adrenaline, and similar hormones, are also responsible for increasing heart rate and constricting blood vessels, leading to elevated blood pressure. Ultimately, when blood sugar falls too far in either direction, blood pressure may be affected.
5 Ways to Support Healthy Blood Sugar and Blood Pressure
Maintain a healthy weight – If overweight, weight loss may prevent disease progression. The Centers for Disease Control and Prevention (CDC) notes that a 5-7% loss of body weight can stop pre-diabetes from developing into diabetes. Similarly, the National Heart, Lung, and Blood Institute (NHLBI) indicates that a 3-5% loss of body weight can improve blood pressure.
Be physically active – Regular physical activity can lower blood pressure and blood sugar levels. Current CDC guidelines recommend 150 min of moderate-intensity exercise or 75 minutes of vigorous exercise each week.
Adopt a healthy dietary lifestyle – It’s essential to find a dietary lifestyle that fits your goals and values, is suitable for you financially, and feels sustainable. The DASH, Mediterranean, or MIND diet lifestyles have been found to support blood pressure, blood sugar, and physical and cognitive functioning. All focus on high intakes of vegetables and include lean proteins, unsaturated fats, high-fiber carbohydrates, and limited salt intake.
Manage stress – Stress can raise both blood sugar and blood pressure. Managing and coping with stress can improve your mental and physical health. Relaxation and meditation apps are available to aid with stress. Other great options include mental health counseling, support groups, time spent with loved ones, or an activity that helps downregulate stress hormones and find rest.
Quit smoking – Smoking can increase the risk of type 2 diabetes by 30-40%. Due to nicotine’s ability to decrease the cellular response to insulin and increase systemic inflammation, cigarette smoking has been found to increase blood sugar. Similarly, nicotine can increase blood pressure by stimulating the release of epinephrine and norepinephrine. Smoking cessation programs have found that both systolic and diastolic blood pressure improve and decrease your risk for type 2 diabetes.
Evidence demonstrates that hyperinsulinemia, most often caused by hyperglycemia and insulin resistance, can lead to hypertension. Furthermore, the bodies response to low blood sugar, the release of catecholamine hormones, can also lead to high blood pressure. Therefore, blood sugar instability in either direction may increase blood pressure levels.
It’s important to note that you don’t have to have a diabetes diagnosis to struggle with blood sugar control and be affected by these negative health consequences. Recent evidence from the University of Alabama at Birmingham found that nearly 40% of young adults without diabetes experience unhealthy blood sugar levels and insulin resistance. With the acknowledgment that fluctuations in blood sugar levels may lead to a cluster of health concerns, including high blood pressure, it’s vital to monitor and regulate blood sugar and blood pressure levels when possible.