More than 40 million Americans are living with diabetes, and roughly 90% of them have type 2 — a number that has climbed steadily for two decades and shows no sign of leveling off. It's often described in simple terms: too much sugar in the blood. But the underlying biology is considerably more interesting than that shorthand suggests, and understanding it helps explain why type 2 diabetes affects nearly every organ system in the body, not just blood sugar itself.
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It Starts With a Cell That Stops Listening
Schematic illustration of the islets of Langerhans in diabetes. © Ilusmedical / Science Source
Type 2 diabetes begins with insulin resistance — a state in which cells throughout the body, particularly in muscle, fat, and liver tissue, become less responsive to insulin's signal to absorb glucose from the bloodstream. Insulin itself is produced by beta cells clustered in small structures within the pancreas called the islets of Langerhans, and in early insulin resistance, those beta cells respond by producing more insulin to compensate, keeping blood sugar roughly in range.
Over time, though, that compensation becomes harder to sustain. Beta cells can lose function under the sustained demand, insulin output falls short of what's needed, and blood glucose levels begin to climb — the point at which type 2 diabetes is typically diagnosed.
A fun fact worth knowing: the islets of Langerhans are named for Paul Langerhans, who identified these clusters of cells in 1869 — as a 22-year-old medical student, no less, decades before anyone understood that they produced insulin or had anything to do with diabetes at all.
Why Blood Sugar Is Only Part of the Story
Chronically elevated glucose doesn't just sit passively in the bloodstream. Over months and years, excess glucose molecules attach to proteins throughout the body in a process called glycation, altering how those proteins function and gradually damaging blood vessels, nerves, and tissue. This is the mechanism that connects "high blood sugar" to the much longer list of complications associated with type 2 diabetes — it's a systemic disease that happens to be diagnosed through a blood sugar number, not a localized one.
Who's Most at Risk?
Medical visualization of a stroke. © TheVisualMD / Science Source
Type 2 diabetes risk is shaped by a mix of factors, some modifiable and some not:
Obesity: the single strongest modifiable risk factor, closely associated with insulin resistance.
Age: risk rises significantly after age 45, as beta cell function tends to decline over time.
Family history and genetics: a first-degree relative with type 2 diabetes meaningfully raises individual risk.
Sedentary lifestyle: physical inactivity is independently associated with insulin resistance, separate from its effect on body weight.
Hypertension: frequently co-occurs with type 2 diabetes and compounds vascular risk.
History of gestational diabetes: significantly raises the likelihood of developing type 2 diabetes later in life.
Ethnicity: CDC data shows higher prevalence among American Indian/Alaska Native, Black, and Hispanic populations compared to non-Hispanic white populations.
The Complications That Follow
Because glycation and vascular damage accumulate throughout the body, type 2 diabetes complications tend to cluster around a few organ systems that are especially vulnerable to blood vessel and nerve damage:
Diabetic retinopathy: damage to the small blood vessels of the retina, and a leading cause of vision loss in adults.
Diabetic neuropathy: nerve damage, most commonly affecting the hands and feet, that can progress from numbness to significant pain or loss of sensation.
Diabetic nephropathy: progressive kidney damage, and one of the leading causes of chronic kidney disease in the U.S.
Cardiovascular disease: elevated risk of heart attack and stroke, driven by the same vascular damage mechanisms discussed in our earlier post on COVID-19 and cardiovascular risk.
Impaired wound healing and peripheral vascular disease: reduced blood flow to the extremities that slows healing and raises infection risk, a complication with real relevance to dermatologic and wound-care imagery.
Not every patient develops every complication, and severity varies considerably. But the breadth of this list is itself instructive — it's a reminder that type 2 diabetes is rarely, if ever, a single-organ disease.
A Disease Written at Multiple Scales
Diabetic Nephropathy. Illustration of a kidney damaged by diabetes. © Monica Schroeder / Science Source
What makes type 2 diabetes a genuinely interesting subject to illustrate is how it plays out across such different scales at once. At the molecular level, it's a story about glucose molecules and insulin receptors. At the cellular level, it's about beta cells losing function and vessel walls accumulating damage. At the level of the whole patient, it's retinas, kidneys, nerves, and hearts. Few diseases require imagery spanning that wide a range — from micrograph to whole-organ illustration — to tell the full story accurately.
A Story Best Told With the Right Imagery
A disease that plays out at this many scales is difficult to capture in a single image — which is exactly why a strong collection matters. From islet cell illustrations to retinal photography to kidney micrographs, the visual range needed to tell this story accurately is broad by nature.
Our collection covers it comprehensively, with accurate metadata behind every asset and more than sixty years of experience helping editors and picture researchers find exactly what a piece requires — at no charge, as part of the research support we offer every client.