The Differences Between Type 1 and Type 2 Diabetes

Michael Albrecht, MD

Apr 09, 2025

Diabetes mellitus (which most people call diabetes for short) is a common condition in the United States. In all forms of diabetes, average blood sugar levels are elevated chronically (long-term). In other words, diabetes doesn’t usually develop overnight and it can last for years or even a lifetime. While there are other forms and causes of diabetes, type 1 and type 2 are the most common types.

Problems develop in our bodies if our blood sugar remains elevated for long periods of time. Without making things too complicated to understand, just know that excessive blood sugar levels can damage our tissues and organs and cause complications over time. The most common complications that uncontrolled diabetes (high blood sugar) levels can cause are nerve damage (leading to numbness/tingling/pain in the feet and hands), kidney damage (which can lead to kidney failure and need for dialysis), and eye damage (which can lead to vision loss and blindness). Having diabetes also greatly increases the risks for heart attacks, strokes, and infections.

Ok, but what’s the difference between type 1 and type 2 diabetes? Many people are confused about which type of diabetes they have. First, about 90% of patients who have diabetes actually have type 2 diabetes. That means only about 10% of people who have diabetes have type 1 diabetes.

Type 1 diabetes is an autoimmune disease. What does that mean? It means that–for largely unknown reasons–these patients’ own immune systems attack and destroy their pancreas. The pancreas is where insulin is made. Insulin, in turn, is a hormone that lowers our blood sugar levels by helping to push the blood sugar into our bodies tissues and organs. Since these patients make little to no insulin, their body lacks the hormone that is needed to lower blood sugar. The consequence is that people with type 1 diabetes are treated with insulin because they require this insulin to survive. Many people who have type 1 diabetes use insulin pumps to administer the insulin, although some of them still inject themselves with insulin multiple times per day rather than using an insulin pump. Again, only 10% of people who have diabetes have this form of diabetes.

Type 2 diabetes, the most common type of diabetes, occurs due to insulin resistance. People who have type 2 diabetes make plenty of insulin (in fact, their blood insulin levels are typically very high). However, their body’s tissues and organs don’t lower blood sugars very much in response to insulin. There are several factors that increase insulin resistance, including genetics. However, the biggest risk factor for having insulin resistance is being overweight (obesity). Diet, exercise, weight loss and medications are used to improve the high blood sugar levels associated with insulin resistance and type 2 diabetes. There are numerous medications now on the market that are used to treat type 2 diabetes, including metformin, SGLT2 inhibitors (e.g., Jardiance, Invokanna, Farxiga), GLP-1 medications (e.g., Ozempic, Mounjaro, Trulicity, Rybelsus), and many others. Insulin is sometimes needed in late stages of type 2 diabetes when patients have tried and failed other options.

What are GLP-1 Weight Loss Drugs?

Michael Albrecht, MD

Mar 19, 2025

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By the time patients get to me in weight management practice, they’ve often heard of the “GLP-1 drugs,” such as Ozempic, Mounjaro, Wegovy, Zepbound, and Saxenda. These are powerful medications that can help people lose weight by 15 to 20% or more of their starting weight. However, one of the most common questions I’m asked in weight loss clinic is: “How do these drugs work?”

After being asked that question, I usually go into my spiel of telling them that GLP-1 medications mimic a hormone that our bodies naturally make called GLP-1 (Glucagon-like Peptide 1). I then go on to tell them how GLP-1 works in our bodies:

The GLP-1 hormone is secreted by our small intestine into the bloodstream continuously by our intestines at low levels, but when we eat carbohydrates (“carbs”), our intestines detect this and secrete a “spike” of GLP-1 hormone into the bloodstream.

What does GLP-1 do after it’s in our bloodstream? First, GLP-1 stimulates the pancreas to increase production of insulin and decrease the production of another hormone called glucagon. The overall effect is to decrease our blood sugar levels. Second, GLP-1 tells the stomach to sloooow dooooown. Doctors call this effect “delayed gastric emptying.” In this way, GLP-1 makes the food we eat stay in our stomach longer, and this helps us feel full quicker. Third, GLP-1 has effects on the brain. It communicates to the brain that we’re not hungry, and thus, GLP-1 is a potent appetite suppressant.

GLP-1 drugs mimic the GLP-1 hormone because they bind to the same receptors as GLP-1 hormone in the body. Thus, these medications help us lose weight by increasing satiety (our sensation that we’re full after eating), and by suppressing appetite. Since the drugs also lower blood sugar, the medications also can be used to treat diabetes. We also have strong evidence that these medications reduce the risk for cardiovascular events such as heart attack and stroke.

These medications are very effective for weight loss. Studies have shown that it is common to experience weight loss of 15 - 20% or more of the initial body weight, depending on the medication.

Unfortunately, there’s always a catch. GLP-1 medications are very expensive and sometimes not covered by insurance. They also can cause side effects, such as nausea, vomiting, constipation, diarrhea, burping, heartburn, fatigue, injection site reactions, and hair loss. Caution is needed to use these medications with a prior history of pancreatitis or with any pre-existing gastrointestinal conditions, such as Crohns disease. Because of a theoretical risk of medullary thyroid cancer based on studies in rats, patients should not use these medications if there is a personal or family history of medullary thyroid cancer or a condition known as MEN 2 syndrome.

The bottom line is that the GLP-1 medications are very effective medications for weight loss. They have a number of positive effects in the body, but are not without side effects or expense. Discuss these medications further with your personal physician to help to understand if these medications are right for you.