It’s been estimated that over 6% of the world’s population is affected by type 2 diabetes.

That’s a lot, more than 400 million people. And it can be a confusing disease, requiring careful management and lifestyle changes, with a lot of conflicting advice floating around out there.

But we are here to help. In this video we’re going to tackle as many questions as we can around type 2 diabetes: what it is, what affects your risk, even whether you need to change your diet. And it’s all going to be based on science.

No fad diets or scam natural remedies, just good old-fashioned research. We’re also including section breaks so you can skip around and search for the thing you’re wondering about most. So here, without further ado, is everything you need to know about type 2 diabetes. [♪ INTRO] Diabetes is an umbrella term for when the pancreas doesn’t produce enough insulin, or when the body can’t properly use the insulin it makes.

Insulin is a hormone that regulates blood glucose, often referred to as blood sugar. That’s because the body converts food into glucose, which is a specific kind of sugar, to distribute it out to cells. Indeed, insulin is often compared to a key that unlocks cells.

When everything is working smoothly, soon after someone eats, elevated glucose levels trigger the pancreas to release insulin. Insulin makes sure the glucose gets into the cells that need it. The locks are way more complicated than anything on your front door, though.

Specific molecules on the surface of cells have a structure that corresponds to the shape of the insulin key. When insulin slots into that structure, the cell responds by opening up and allowing sugar molecules to enter. When diabetes is uncontrolled over time, hyperglycemia, or spikes of excessive glucose in the bloodstream, leads to serious damage to many of the body's systems, especially the nerves and blood vessels.

We’re focusing today on type 2 diabetes, but it’s worth pointing out that the categories this disease falls into aren’t as rigid as they seem. Type 1 diabetes is usually defined as an autoimmune condition that attacks the pancreas and is usually diagnosed in childhood. In these people, cells in the immune system mistake insulin-producing cells in the pancreas for foreign invaders that don’t belong in the body, and nuke their ability to do their job.

Type 2 diabetes has been defined as a problem with energy processing that occurs later in life. Type 2 is thought to make up over 90% of diabetes cases. In these people, the pancreas is making some insulin, but the cells just don’t let glucose in very efficiently.

This is referred to as insulin resistance. A third major type of diabetes is gestational diabetes, in which a person is thought to develop hyperglycemia temporarily during pregnancy. Then there are other forms like neonatal diabetes, a rare condition in which a genetic mutation affects the production or function of insulin starting before 6 months of age.

The concept of prediabetes gained traction in the late 1970s as a term for the stage between what’s considered normal blood sugar and Type 2 diabetes. The idea is that it takes a while to start noticing the classic symptoms, like excessive urination, because they take a while to develop as hyperglycemia progresses. To this day, there isn’t one consistent definition of prediabetes.

However, some physicians still advocate for pre-diabetes as a category because being diagnosed with it can be like an early alert signal. Basically, it’s thought that most everyone who develops type 2 diabetes has pre-diabetes first. Knowing that you have it may allow people to make changes to their diet and physical activity, and/or take medications, to prevent progression to Type 2 diabetes.

Some researchers have encouraged viewing the various types of diabetes as more of a spectrum because some people have elements of more than one. For instance, evidence increasingly suggests that there can sometimes be an autoimmune component in Type 2 diabetes as well. Insulin works as part of a complex, interconnected network of molecules that each play their own roles in getting glucose into cells.

Molecular biologists call these complex interactions pathways – think of it like a bunch of different molecules tossing messages to one another. Many steps in these chain reactions are simply necessary for insulin to be able to do its job. Individuals with too many hiccups in these pathways eventually develop insulin resistance and hyperglycemia.

When cells increasingly stop responding to insulin knocking on their proverbial doors over a matter of years, initially, the pancreas starts making even more insulin to compensate. But the cells increasingly stop responding. Over time, cells that produce insulin in the pancreas decrease in number and lose functionality.

Between the reduced response to insulin and the eventual decline of insulin secretion, the amount of glucose in the blood gets out of whack. Researchers have identified a few ways that insulin resistance and hyperglycemia damage the human body on a molecular level, leading to larger damage to tissues and organs. It all seems to happen in a sort of vicious cycle.

They have identified hundreds of variations in genes that can mess with various functions in these pathways. So many variations appear to be involved that this disease has been called a geneticist’s nightmare. To further complicate things, in addition to genetic differences that people are born with, there are also differences in how genes are turned on or off.

Some differences may even be related to the microbiome, or the community of bacteria and other microbes in our body. All of this leads to large-scale effects on the body – the symptoms of type 2 diabetes. The body undergoes cumulative injuries as insulin resistance gets worse and the pancreas is increasingly affected.

The potential consequences include vision problems or blindness, kidney disease that can progress to kidney failure, cardiovascular disease, increased incidence of heart attack and stroke, and lower limb amputation. Over time, the inflammation, plaque buildup, and cell death that result from type 2 diabetes weaken the walls of the vascular system. This is largely due to microscopic tears in capillaries or even bigger hemorrhages in the blood vessels.

There is also damage to various types of cells that are important to organ function, which affects pretty much the whole body. Like the liver. When someone’s blood sugar is well-controlled, the liver stores glucose and releases it when the body needs energy.

When glucose isn’t getting stored in the liver the way it should, the stress on the liver leads to damage over time. Diabetes also damages nerve cells, which is why some people experience tingling, pain, weakness, and numbness, which can be mild or severe, in the extremities. Cells that work to filter blood in the kidneys get hurt too.

The excess blood sugar makes the kidneys work overtime to remove it from the blood, which requires more water, hence the increased thirst and urination in those whose diabetes isn’t well controlled. Over time, around 1 in 3 people with Type 2 diabetes will also be diagnosed with chronic kidney disease. But let’s turn to what puts you at risk for developing type 2 diabetes in the first place.

People often hear that lower physical activity levels, higher body mass, or even eating too much sugar are among the biggest contributors to developing Type 2 diabetes. But while these claims are widespread, even among doctors, they are an oversimplification at best, and misleading and harmful at worst. That’s why the idea that poor individual choices cause Type 2 diabetes has been increasingly challenged.

On a population level, those with higher body weight are more likely to have Type 2 diabetes. Having excess body weight is a risk factor for Type 2 diabetes. But like other risk factors, weight doesn’t necessarily predict individual risk— you can’t look at two people and assume that the one with more body fat would be the one who develops diabetes.

Then there are risk factors, including social factors, that don’t fall under some of these more typical assumptions. Like having a lower income, housing or food insecurity, or having had COVID-19, especially in the early phases of the pandemic. /All/ of this is just an abridged list of factors that play a role in Type 2 diabetes. And researchers are also unlearning so much of what they thought they knew.

Like, scientists once believed that racial and ethnic disparities in T2D prevalences and outcomes are due to higher genetic risk in certain groups. But most researchers have walked that back now that it’s becoming increasingly clear that race, and even ethnicity, are social constructs. It’s not “race” that causes higher rates of diabetes – rather, it’s structural injustice and inequity leading to differences in the environment that results in increased Type 2 diabetes incidence and poorer outcomes.

So rather than just individual differences, there’s a growing push to address structural factors that contribute to people developing Type 2 diabetes. These include making sure that everyone lives, works, and plays in health-promoting environments with plenty of access to nutritious food, green spaces, education, and low levels of exposure to harm. While researchers continue to unpack how all of it works, we know quite a bit of actionable information about how to keep Type 2 diabetes in check.

First, to know whether someone has diabetes, a doctor will usually measure what’s called their hemoglobin A1C levels. This test looks at the proportion of a specific type of hemoglobin in the blood that’s chemically linked to sugar. Since blood cells have a lifespan of about three or four months, this figure is a representation of blood sugar levels over that period.

It’s a better indicator of Type 2 diabetes than a one-time blood sugar measurement, which can be thrown off by various factors. According to the Centers for Disease Control and Prevention, an A1C measurement of 5.7 percent or below is normal, and 5.7 to 6.4 percent is in the pre-diabetic range. Someone is diagnosed with Type 2 diabetes when they have an A1C of over 6.5 percent or higher measured on two separate occasions.

People with Type 2 diabetes need to keep their blood sugar from going too low or too high throughout the day, but also ideally to reduce their A1C measurements over time. This doesn’t require completely cutting sugar or following any particular fad diet. More than any specific type of diet, the general advice for preventing or managing Type 2 diabetes is to eat fruits and vegetables, whole grains, legumes, complex carbohydrates paired with fiber, and healthy fats.

Minimizing added sugars is also a good thing, although this doesn’t mean that people with diabetes can never eat cake. It’s ideal for people diagnosed with Type 2 diabetes to work with a registered dietitian to come up with individualized guidance on what to eat. When you eat and how often you eat will also come into play, and it makes sense to talk to a trained professional to help suit your eating habits to your way of life.

Basically, use common sense and talk to your doctor. Anyone telling you to eat or not eat some incredibly specific thing? They are probably selling something.

Physical activity is also important for managing Type 2 diabetes. Again, researchers still working out how this works on a molecular level, but moving around can help undo some resistance to insulin and help glucose get into cells. While there is ongoing research into how often or how hard someone needs to exercise to help control their type 2 diabetes, the general advice is to get at least 150 minutes of moderate physical activity per week, including both aerobic exercise and strength training.

When it’s not feasible for someone with Type 2 diabetes to keep their A1C and blood sugar in check with just lifestyle modifications, a drug called metformin is the first that doctors typically prescribe. In people with pre-diabetes, it’s been shown to prevent progression into full-blown diabetes. Metformin seems to act in a few ways, one of which is to help insulin signaling and the uptake of glucose by cells.

Insulin injections are used when someone’s pancreas just can’t make enough insulin on its own. Unlike metformin, insulin is known for being incredibly expensive, so controlling its price has been called a human rights issue. Then there is a well-known, newer drug called semaglutide that’s marketed under names like Ozempic and Wegovy, which are administered by injection.

It works by doing a few things, including increasing insulin production by the pancreas and slowing digestion. This drug can also lead to weight loss, with some people who take it reporting a reduced appetite. We’ve heard a lot about how the drug has been increasingly used for weight loss in people without diabetes.

But until recently, it was prescribed specifically for Type 2 diabetes. There’s unlikely to ever be a cure for Type 2 diabetes, but technically, a kind of remission is possible. Someone can be said to be in remission when their A1C stays below 6.5 percent for over three months without any medication.

Lowering A1C is usually achieved through a combination of changing eating habits, moving more, and sometimes using medications. The question is whether that remission can last, and how long it can last. It is still considered a fairly new concept, and many open questions remain.

Based on what we know so far, in a certain subset of people, remission seems to depend on reducing and maintaining a lower body mass. So there you have it: everything you need to know that we could cram into a video of this length. Short version: Diabetes is not a death sentence, and it can be managed with medication and lifestyle changes.

Which ain’t nothing, but it’s doable. If you have more questions, add them in the comments. And feel free to share this video with anyone who needs it.

This episode of SciShow was made possible by our patrons on Patreon. You guys are awesome and we’re so grateful for your support. Thanks for watching, and we’ll see you next time. [♪ OUTRO]