Type 2 diabetes is a chronic condition characterized by persistently high blood sugar levels (hyperglycemia). This occurs when the body either doesn’t produce enough insulin, a hormone that helps glucose enter cells for energy, or its cells don’t respond properly to insulin (insulin resistance). While manageable, uncontrolled high blood sugar over time can lead to serious health complications. This article explores how elevated blood glucose can damage different organ systems and tissues.
Cardiovascular Complications
Type 2 diabetes significantly increases the likelihood of developing heart and blood vessel diseases. These complications are a leading cause of illness and death for individuals with the condition. Conditions like coronary artery disease (which can lead to a heart attack), stroke, and peripheral artery disease are more prevalent and often occur earlier in people with type 2 diabetes.
The primary mechanism behind these cardiovascular issues is accelerated atherosclerosis, a process where arteries harden and narrow due to plaque buildup. High blood sugar levels promote endothelial dysfunction, the initial factor in diabetic vascular complications. Insulin resistance, inflammation, and the formation of advanced glycation end products (AGEs) also contribute to this arterial damage, leading to reduced blood flow and an increased risk of blood clots.
A long-term study involving over 1,200 patients demonstrated that type 2 diabetes is an independent predictor of major adverse cardiovascular events, with a significantly higher incidence in those with diabetes compared to non-diabetic individuals. This underscores the widespread impact of diabetes on the circulatory system, leading to a higher burden of atherosclerotic plaque and smaller coronary artery lumen diameters.
Kidney, Nerve, and Eye Complications
High blood sugar can severely affect the small blood vessels throughout the body, leading to microvascular complications in organs like the kidneys, nerves, and eyes. These complications can significantly impair organ function over time.
Diabetic Nephropathy (Kidney Disease)
Diabetic nephropathy, or kidney disease, arises when prolonged high blood glucose damages the kidney’s filtering units. This damage involves metabolic factors like advanced glycosylated end products (AGEs), hemodynamic changes, and increased inflammation. Initially, the kidneys may experience hyperfiltration, but over time, this progresses to impaired function, characterized by albuminuria (protein in the urine) and a decline in glomerular filtration rate. Left unmanaged, this can lead to chronic kidney disease and eventually kidney failure, potentially requiring dialysis or a kidney transplant.
Diabetic Neuropathy (Nerve Damage)
Diabetic neuropathy refers to nerve damage caused by long-term high blood sugar levels, which disrupts the small blood vessels supplying the nerves. Peripheral neuropathy, the most common type, affects nerves in the feet, legs, hands, and arms, often causing numbness, tingling, burning sensations, or sharp, jabbing pain, particularly at night. Autonomic neuropathy impacts nerves controlling internal organs, potentially leading to digestive issues like gastroparesis (slow stomach emptying), bladder problems, sexual dysfunction, and changes in heart rate or blood pressure. Proximal neuropathy, more common in older adults with type 2 diabetes, causes pain and weakness in the thighs, hips, or buttocks.
Diabetic Retinopathy (Eye Damage)
Diabetic retinopathy involves damage to the tiny blood vessels in the retina, the light-sensitive tissue at the back of the eye. High blood sugar can cause these vessels to leak fluid or blood, leading to blurred vision and, if severe, the growth of new, fragile blood vessels that can hemorrhage and cause scar tissue formation. This can result in significant vision impairment or blindness. Individuals with diabetes also face an increased risk of developing cataracts, a clouding of the eye’s lens, and glaucoma, a condition characterized by increased eye pressure that can damage the optic nerve.
Foot and Skin Health Complications
Diabetes can lead to serious issues affecting both the feet and the skin, often stemming from nerve damage and impaired circulation.
Foot Complications
Foot complications in diabetes are largely driven by diabetic neuropathy, which reduces sensation in the feet, making injuries and sores go unnoticed. Poor circulation, often due to peripheral artery disease, further impairs the body’s ability to heal wounds. This creates an environment where even minor cuts or blisters can develop into chronic foot ulcers. These ulcers are prone to infection, and if left untreated, can lead to tissue death, gangrene, and ultimately require amputation of a toe, foot, or part of the leg. Diabetic foot ulcers are a leading cause of non-traumatic lower extremity amputations.
Skin Health
Skin health is also frequently affected by type 2 diabetes. Individuals with diabetes are more susceptible to bacterial and fungal infections due to a weakened immune system, as high blood sugar can weaken white blood cells. Common skin infections include fungal infections like candidiasis and bacterial infections such as boils or carbuncles. Beyond infections, specific diabetes-related skin conditions can emerge:
Acanthosis nigricans presents as dark, velvety patches of skin, typically found in the armpits, neck, groin, and other skin folds, and often signals insulin resistance.
Diabetic dermopathy, also known as “shin spots” or “pigmented pretibial patches,” appears as small, brown, scaly spots, most commonly on the shins.
Necrobiosis lipoidica diabeticorum is a rarer condition characterized by reddish or purplish lesions that evolve into shiny, yellowish plaques, usually on the legs, which can be painful or ulcerate.
Other Systemic Complications
Hearing Impairment
Individuals with type 2 diabetes have an increased risk of hearing impairment, which may be linked to the damage high blood sugar causes to the tiny nerve fibers and blood vessels in the auditory system. This can lead to difficulties in processing sound signals, potentially worsening over time with prolonged diabetes duration.
Dental Problems
Dental problems, particularly gum disease (periodontal disease) and tooth loss, are also more common in people with diabetes. High blood sugar levels can weaken the immune response in the mouth and increase sugar in saliva, fostering bacterial growth that contributes to gum inflammation and infection.
Mental Health and Cognitive Decline
Type 2 diabetes is linked to mental health conditions, including depression and anxiety, with depression affecting a significant proportion of individuals with diabetes. The disease can also be associated with cognitive decline, with a connection between type 2 diabetes and reduced cortical thickness in brain regions associated with memory and cognitive function.