Diabetes

Background

Diabetes mellitus is a chronic, progressive disease caused by a lack of, or problems with processing, the hormone insulin. The result is persistently high glucose (sugar) in the blood, causing symptoms including slow-healing wounds, exhaustion, and increased thirst.

Roughly one in 10 adults have diabetes globally. The condition is considered an epidemic by the World Health Organization, though a quarter of adults with diabetes don't know they have the disease (see stats here). 

Physiology

The body breaks down the food we eat into usable molecules. One of these is glucose, the body's main source of energy. It can be used by the body immediately or stored in the liver and muscles as glycogen for later use.

Once glucose hits the bloodstream—for example, after meals—the pancreas is responsible for controlling the body’s blood sugar level, jumping into action if it is too low or too high.

If blood sugar is too low, a molecule called glucagon is released, signaling to the body to convert and release stored sugar. When blood sugar is too high, the pancreas releases insulin, telling the body to send glucose to cells to use or store.

If the pancreas doesn’t release enough insulin, or cells don’t respond to insulin properly, glucose levels remain persistently high. This may eventually lead to a variety of serious health concerns—hardened blood vessels, damaged organs, high blood pressure, blindness, kidney disease, heart attacks and strokes, and even death.

Pathology

There are two primary types of diabetes: Type 1 and Type 2. Gestational diabetes occurs in 2% to 10% of pregnancies and typically manifests in mild symptoms (see overview), though they may get worse for the baby and mother if left untreated.

Type 1 diabetes—formerly known as juvenile-onset diabetes—is a partially inherited autoimmune condition in which the body’s immune system attacks insulin-producing cells in the pancreas, undermining and potentially halting all production of the hormone.

Its exact cause is unknown (watch overview). A number of heritable genetic risk factors have been implicated, but they appear to often be triggered by environmental factors. Roughly 5% to 10% of diabetics fall into this category.

Type 2 diabetes occurs when your cells don’t respond normally to insulin or the pancreas can’t keep up with the amount of insulin needed to lower blood sugar levels.

While some genetic factors exist, primary drivers include diet (sugary or high in carbohydrates), lack of exercise (which lowers blood sugar by burning energy), and obesity (which reduces the ability of insulin to reach cells).

Treatment

First recognized in 1500 BCE, diabetes was a "uniformly fatal" condition for centuries until the discovery of insulin supplements in the 1920s. 

Modern treatments typically hinge on such supplements, often administered as injections, though people with Type 2 diabetes can sometimes manage their condition with medication (see timeline).

Researchers are also exploring other potential treatments for the manageable disease, including cell therapy, fecal transplants, artificial pancreas, and pancreas stem cell manipulation.