Diabetes is a chronic health condition characterized by elevated blood sugar levels, or hyperglycemia. This occurs either when the pancreas does not produce enough insulin, a hormone that regulates blood glucose, or when the body cannot effectively use the insulin it produces. Over time, consistently high blood sugar can damage various bodily systems, particularly nerves and blood vessels, leading to a range of complications.
Understanding Microvascular Damage in Diabetes
The term “microvascular” refers to the smallest blood vessels in the body, specifically arterioles, venules, and capillaries. These tiny vessels deliver oxygen and nutrients to tissues and remove waste products. In individuals with diabetes, prolonged exposure to high blood glucose levels, or chronic hyperglycemia, is the underlying cause of damage to these microvessels.
High blood sugar triggers cellular changes like endothelial damage and oxidative stress. This leads to a progressive thickening and increased rigidity of the basement membranes surrounding the capillaries. As these membranes thicken, the lumen, or inner space of the blood vessel, narrows.
This impairs blood flow, reducing oxygen and nutrient delivery to tissues. The capillaries also become abnormally permeable, allowing proteins and fluids to leak out, further compromising tissue function.
Specific Microvascular Complications
Diabetes can lead to specific microvascular complications, each affecting different parts of the body. These include diabetic retinopathy, nephropathy, and neuropathy.
Diabetic Retinopathy
Diabetic retinopathy is an eye disease resulting from damage to the blood vessels in the retina, the light-sensitive tissue at the back of the eye. High blood sugar can cause these vessels to swell and leak fluid, or they can become blocked, cutting off blood supply to parts of the retina. In more advanced stages, fragile new blood vessels may grow on the retina’s surface, a process called neovascularization. These new vessels are prone to bleeding into the vitreous, the clear gel that fills the eye, which can cause vision problems ranging from dark floaters to complete vision blockage.
Early symptoms are often absent. As the condition worsens, individuals may experience blurred or distorted vision, new color blindness, night blindness, eye floaters, or blind spots. Macular edema, a swelling of the macula (the central part of the retina) due to leaking fluid, is a common reason for vision loss in people with diabetes. The condition can ultimately lead to severe vision loss or permanent blindness.
Diabetic Nephropathy
Diabetic nephropathy refers to kidney damage from diabetes. Prolonged high blood sugar harms the tiny blood vessels within the kidneys, known as glomeruli, which filter waste products. This damage impairs the kidneys’ ability to function, leading to a buildup of waste in the body and potentially progressing to kidney failure. High blood pressure, often co-occurring with diabetes, can further exacerbate this kidney damage by increasing pressure within the filtering system.
Early stages of diabetic nephropathy usually present no symptoms. As kidney damage advances, symptoms may become noticeable and include swelling in the feet, ankles, hands, or around the eyes due to fluid retention. Other symptoms include foamy urine, fatigue, loss of appetite, nausea, and difficulty concentrating. In severe cases, a metallic taste in the mouth or muscle twitching may occur as waste products accumulate.
Diabetic Neuropathy
Diabetic neuropathy is nerve damage caused by high blood sugar. Elevated glucose levels can injure nerves throughout the body, often affecting those supplied by small blood vessels. This damage can manifest in various ways depending on which nerves are impacted, with symptoms usually developing slowly over time.
Peripheral neuropathy is the most common form, primarily affecting the nerves in the feet and legs, and sometimes the hands and arms. Symptoms often include numbness, a tingling or burning sensation, sharp pains, or cramps. Individuals may also experience increased sensitivity to touch, where even light contact can be painful, or a loss of feeling, reducing their ability to detect pain or temperature changes. This can lead to serious foot problems, such as ulcers and infections, due to unnoticed injuries.
Autonomic neuropathy involves damage to nerves that control involuntary bodily functions, such as blood pressure, heart rate, digestion, and bladder control. Symptoms can be varied, including a lack of warning signs for low blood sugar (hypoglycemia unawareness), dizziness or fainting due to drops in blood pressure when standing, and a fast heart rate at rest. Digestive issues like slow stomach emptying (gastroparesis), causing nausea and vomiting, or problems with bladder and bowel function, are also possible.
Preventing and Managing Microvascular Complications
Preventing the onset or slowing the progression of microvascular complications relies on consistent management strategies. Maintaining strict control over blood glucose levels is a primary defense against these complications. Regular monitoring of blood sugar, often multiple times a day, and adhering to prescribed medications or insulin regimens are important to keep glucose within target ranges. Lifestyle adjustments, including a balanced diet and regular physical activity, play a significant role in achieving and sustaining glycemic control.
Managing blood pressure is equally important, as high blood pressure can worsen microvascular damage. Individuals with diabetes should work with their healthcare providers to achieve and maintain blood pressure targets, often through medication and lifestyle changes. Cholesterol management, including maintaining healthy levels of LDL (low-density lipoprotein) and triglycerides, also contributes to reducing the risk of vascular complications.
Regular screenings are an important part of detecting microvascular complications early, allowing for timely intervention. This includes routine dilated eye exams to check for diabetic retinopathy, kidney function tests such as urine albumin-to-creatinine ratio (UACR) and estimated glomerular filtration rate (eGFR) for nephropathy, and comprehensive foot exams to assess for neuropathy. Adopting a healthy lifestyle, which encompasses a balanced diet, consistent physical activity for at least 30 minutes most days of the week, maintaining a healthy weight, and avoiding smoking, collectively supports overall health and reduces the risk of complications.