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?
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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.
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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.
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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.