about type 2 diabetes

Type 2 diabetes is a national health crisis

If you are an adult living in the United States, you are now more likely than not to either have type 2 diabetes or be on your way to developing it. 14.3% of US adults have type 2 diabetes, and 38.0% of US adults have prediabetes, meaning that 52.3% of the adult population in the US is suffering from metabolic disease.

What is Type 2 Diabetes?

At the most basic level, diabetes is a term used to describe a group of diseases that result in high blood sugar. Type 2 diabetes, (also called diabetes mellitus type 2) represents about 95% of what is generically called “diabetes.” Early in its course, type 2 diabetes is characterized by the combination of very high insulin levels and high blood sugar. In a person without diabetes, such high insulin levels would rapidly reduce blood sugar to normal, but in type 2 diabetes the body becomes resistant to the action of insulin (also known as ‘insulin resistance’), making blood glucose levels hard to control with insulin and other standard medications.

Prediabetes is used to describe an earlier stage of insulin resistance where blood sugar that is elevated above normal, but not high enough to be called type 2 diabetes. An American Diabetes Association expert panel estimated that up to 70% of individuals with prediabetes will eventually develop diabetes. But because prediabetes has few obvious symptoms, 90% of people with prediabetes don’t know they have it.

What are the symptoms?

Type 2 diabetes symptoms include:

  • Fatigue
  • Increased thirst and dry mouth
  • Increased urination
  • Frequent vaginal or urinary infections
  • Erectile dysfunction
  • Increased hunger
  • Neuropathy (numbness, tingling in feet and hands)
  • Blurred vision
  • Slow-healing sores or frequent infections
  • Weight gain

Prediabetes symptoms include:

  • Feeling tired and hungry all the time
  • Poor sleep
  • Difficulty focusing
  • Neuropathy (numbness, tingling in feet and hands)1
  • Skin darkens in the neck, armpits, and skin folds
  • Developing many small skin tags
  • Weight gain, particularly around the waist

How do you know if you have type 2 diabetes?

Type 2 diabetes

At least one the following blood tests:

  1. Fasting blood sugar of 126 mg/dL or higher on two separate occasions
  2. HbA1c of 6.5% or higher
  3. An oral glucose tolerance test that shows a blood sugar of 200 mg/dL or higher after 2 hours


At least one the following blood tests:

  1. Fasting blood sugar of 100-125 mg/dL on two separate occasions
  2. HbA1c of 5.7-6.4%
  3. An oral glucose tolerance test that shows a blood sugar of 140 mg/dL or above after 2 hours. 

Where does high blood sugar come from?

Everyone has glucose, a type of sugar, in their blood at all times. Sugar is a source of energy—it can supply the cells in your body with the energy they need to perform critical functions, ranging from powering your brain to fueling your muscles during high intensity exercise.

When eating a standard American diet, most of the sugar in your blood comes from a particular food source— carbohydrates, also called carbs. Starchy foods such as bread, potatoes, pasta, rice, baked goods and table sugar are commonly referred to as carbs, but “carbs” actually refers to a type of molecule inside these foods.

There are also high levels of carbohydrate molecules in most fruit, fruit juices, sugary beverages, and starchy vegetables such as carrots, yams, corn, dried beans, and peas. In contrast, there are low levels of carbohydrate molecules in non-starchy vegetables such as leafy greens, cucumbers, green beans, peppers, and broccoli. Carbohydrate molecules like starch are just chains of sugar units, but your body can’t absorb the long chains. During digestion, your body breaks down these chains of sugar units into pieces that it can absorb. These pieces are sugar molecules, most of which are glucose (blood sugar). That’s why when you eat foods containing carbs, it raises your blood glucose—you are absorbing the sugar directly into your bloodstream.

The Role of Insulin

Once this sugar has been absorbed into your bloodstream, it still has to travel a bit farther—in order to be used for energy, the sugar circulating in your blood needs to get inside your cells. That’s where insulin comes into play. Insulin is a chemical messenger produced by your body — a hormone that also helps with growth, fat storage and energy use. Insulin helps move the sugar from out of your blood into your cells, so that it can be used for energy.

Eating carbohydrates results in an increase in blood sugar. Insulin is needed to keep that increase to a minimum. So each time you eat carbohydrates and your blood sugar rises, your body then releases insulin in order to move the sugar into the cells. But if for some reason the body stops responding to the signal of insulin, then the sugar cannot adequately enter your cells, and so it stays in your blood. This causes high blood sugar.

Insulin Resistance

Type 2 diabetes is caused by insulin resistance, a condition in which cells stop responding properly to the signal of insulin. While the root causes of insulin resistance are not fully understood, the bottom line is that adding more insulin does not fix the underlying problem. While your insulin will still rise in response to eating carbohydrates, since your cells are not responding to its signal, your blood sugar cannot be moved into cells effectively. This leaves you with both high blood sugar and high insulin.

Over many years, trying to compensate for the chronically elevated blood sugar requires that your body pumps out insulin at a much higher rate than it’s supposed to. Once we reach adulthood, our ability to grow new insulin-producing cells in the pancreas is limited, so when insulin production is over-stressed, these cells are lost and not replaced. That’s why long-term type-2 diabetes can lead to a loss of the ability to produce much insulin on your own. When you lose most of your ability to produce insulin on your own, that is called pancreatic burnout. At this stage in the progression of type 2 diabetes, injected insulin becomes necessary to replace your body’s dwindling supply.

Insulin resistance is associated with many health problems in addition to type 2 diabetes and prediabetes, including metabolic syndrome, polycystic ovary syndrome (PCOS), atherosclerotic heart disease, fatty liver disease, and more.

High blood sugar is a sign of carbohydrate intolerance

Normal blood sugar is generally considered to be a fasting blood sugar under 100 mg/dL, or 70-140 mg/dL 2 hours after a meal. This is equivalent to about 1 teaspoon of sugar circulating in your blood.

Your body tries to keep your blood sugar in this range because high blood sugar can cause serious damage to your blood vessels and organs, leading to some of the terrible outcomes associated with type 2 diabetes like blindness, kidney failure, and amputations. So when your blood sugar starts to climb above this normal range, your body will markedly increase its insulin secretion to move the additional sugar out of your blood and into your cells.

When you eat food that has a lot of carbs in it, like a cup of white (or even brown) rice, your blood sugar will climb rapidly. This occurs because the carbs in the rice are rapidly converted to sugar. In fact, 1 cup of rice has about 45 grams of carbs in it, which means about 9 teaspoons of sugar is going to be absorbed into a system that tries to stay at about 1 teaspoon of sugar at all times.

For some people, getting their blood sugar down to normal after a high carb meal is relatively easy. They are very sensitive to the signal of insulin, meaning their body can efficiently move the sugar of their blood and into their cells. This can be thought of as a high carbohydrate tolerance, as they can respond to eating a lot of carbs without having blood sugar problems.

But for people with type 2 diabetes or prediabetes, getting their blood sugar down to a normal level after a high carb meal is extremely difficult. These people are resistant to the signal of insulin, meaning their body is struggling to move all of that sugar out of their blood and into their cells, leaving their blood sugar high. This can be thought of as low carbohydrate tolerance or carbohydrate intolerance. For many people, particularly those with a family history of diabetes, years of exposure to a standard diet (typically providing the equivalent of 10-15 teaspoons of sugar per meal) leads to increasing insulin resistance and carbohydrate intolerance.

If you imagine the cells as tiny storage lockers, then insulin is the key that opens the locker doors. When you have type 2 diabetes, you are already struggling with chronically elevated blood sugar due to insulin resistance - so you are already carbohydrate intolerant. In someone who is carbohydrate intolerant, a much higher level of insulin is needed to reduce their blood sugar to a normal level than in someone who is not carbohydrate intolerant. So, carbohydrate intolerance means that for an equal amount of carbohydrates consumed, the insulin needed to keep blood sugar from rising is much greater.