There is a clear link between diabetes and arthritis. Close to 50% of adults living with diabetes have some sort of arthritis or joint pain. And it’s also true the other way around, as people with arthritis have a 60% increased risk of having diabetes.
The relationship and mechanisms aren't fully understood yet and scientists are still researching the topic. But both common risk factors and direct influences of these chronic diseases on each other have been identified.
Here’s an overview of what we know about the links between diabetes and arthritis and what still needs to be explored.
Diabetes and Arthritis
To understand the relationship between diabetes and arthritis, you first need to understand what these two conditions are exactly. There are several types of diabetes and numerous forms of arthritis. Not all of them are linked.
What is diabetes?
Diabetes is a chronic health condition that causes high blood sugar levels. There are three main types of diabetes for which the causes, mechanisms, and treatments vary greatly.
Type 2 diabetes is the most common form of diabetes. It happens when your body does not produce enough insulin or can’t use it efficiently. Insulin is a hormone that helps move sugars from your bloodstream into your cells for energy. In type 2 diabetes, the cells respond poorly to insulin, so the glucose (sugar) stays stuck in the blood. Type 2 diabetes mostly occurs in adults, but it may also affect children. The main risk factors are genetics, obesity, a sedentary lifestyle, and others.
Type 1 diabetes is rarer and concerns only 10% of all people with diabetes. It's an autoimmune disease where the pancreas can't produce insulin or produces too little of it. The consequences are similar to type 2 diabetes: the sugar can’t enter the cells without insulin, so it stays in the bloodstream. Risk factors for type 1 diabetes do not depend on diet and lifestyle. What causes this autoimmune form of diabetes is still unclear, although scientists have proven that genes and environmental factors like viruses, emotional stress, or others are often involved.
Another common form of diabetes is gestational diabetes, affecting pregnant women. Other types of diabetes include prediabetes, as well as specific types like monogenic diabetes, or chemical-induced diabetes.
Whether type 1 or type 2 diabetes is involved, the relationship between diabetes and arthritis isn’t the same. It also depends on the form of arthritis.
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What is arthritis?
While the term arthritis generally refers to joint pain or joint disease, there are more than 100 types of arthritis, including osteoarthritis, rheumatoid arthritis, psoriatic arthritis, spondyloarthropathies, gout, infectious arthritis, and many others. The causes, symptoms, and treatments are very different.
Two forms of arthritis are particularly relevant when exploring the links with diabetes: osteoarthritis and rheumatoid arthritis.
Osteoarthritis is the most common form of arthritis, and it affects millions of people. It's a degenerative joint disease where the flexible tissue (cartilage) at the ends of the bones gradually deteriorates. Anyone can develop osteoarthritis, but the most common risk factors are age, overweight, repetitive stress on the joints, heredity, as well as metabolic diseases like diabetes, hyperlipidemia, or hemochromatosis.
Rheumatoid arthritis is different. Like type 1 diabetes, it's an autoimmune disease where the body's immune system attacks the lining of the joints. Like many other autoimmune diseases, the causes of rheumatoid arthritis are still unknown. However, some factors known to increase the risks are certain genes or external factors such as viruses, emotional stress, or others. These are the same risk factors we’ve identified for type 1 diabetes.
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While many of the links between the different types of diabetes and forms of arthritis are still to be discovered, scientists have clearly identified two relationships. The first one is between type 1 diabetes and autoimmune types of arthritis like rheumatoid arthritis. The second one is between type 2 diabetes and osteoarthritis.
Type 1 Diabetes and Rheumatoid Arthritis
Both type 1 diabetes and rheumatoid arthritis are autoimmune diseases that sometimes coexist.
Two autoimmune diseases
Autoimmune diseases are disorders of the immune system where the body mistakenly attacks healthy cells. In type 1 diabetes, the pancreas cells responsible for insulin production are attacked. In rheumatoid arthritis, the joints are targeted. Psoriatic arthritis and ankylosing spondylitis are other autoimmune types of arthritis and may be a concern too.
When genetic factors are involved, autoimmune diseases sometimes go hand in hand. It’s scientifically proven that people who have one autoimmune disease are more likely to have another one.
Regarding type 1 diabetes and rheumatoid arthritis particularly, one study presented in the European Congress of Rheumatology in 2019 found that people with type 1 diabetes are at higher risk of developing rheumatoid arthritis and inflammatory bowel disease, another autoimmune condition.
Data show that type 1 diabetes is often diagnosed prior to arthritis, which somehow suggests that type 1 diabetes may be a predisposition to rheumatoid arthritis.
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Type 2 Diabetes and Osteoarthritis
People with type 2 diabetes are more likely to have osteoarthritis. Numbers are pretty clear as more than half of type 2 diabetics will develop osteoarthritis.
Common risk factors and direct implication
Here, the relationship does not lie in genetics but rather in common external factors such as age, weight, and lack of physical activity. Age, obesity, and inactivity are identified risk factors for both type 2 diabetes and osteoarthritis.
Besides, high blood glucose levels may have a direct impact on joint health by damaging the cartilage. Recent studies show that high blood sugar over time increases the production of pro-inflammatory cytokines and advanced glycation end products (AGEs) that cause joint inflammation and damage.
Thus, while type 2 diabetes and osteoarthritis share common risk factors, type 2 diabetes may also be a direct cause of osteoarthritis.
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Other Links Between Diabetes and Arthritis
While the mechanisms are yet to be explored and understood, scientists do believe there are other links between diabetes and arthritis.
Inflammatory types of arthritis like rheumatoid arthritis, psoriatic arthritis, juvenile idiopathic arthritis, ankylosing spondylitis, and gout are characterized by an inflammation of the joints.
Type 2 diabetes is not an inflammatory disease, but studies have found that type 2 diabetics have higher levels of inflammation in their body, which increases the risk of developing inflammatory conditions like arthritis. It also works the other way around as inflammation inside the body is also proven to increase insulin resistance and the risk of developing type 2 diabetes.
While the precise mechanisms are yet to be studied, these data clearly show that people who have inflammatory arthritis like rheumatoid arthritis are at higher risk of having type 2 diabetes, and vice versa.
Another possible relation between diabetes and arthritis lies in medications.
Anti-inflammatory arthritis therapies sometimes use steroid drugs like prednisone. These drugs often cause undesirable side effects, including increased blood sugar levels. When taken for long periods of time and at a high dosage, these arthritis medications may increase the risk of developing type 2 diabetes.
Surprisingly, some arthritis medications may reduce the risks of developing diabetes too! Tumor necrosis factors inhibitors (TNF-inhibitors) used in the treatment of rheumatoid arthritis like Humira, Cimzia, Enbrel, Simponi, or Remicade are proven to lower blood sugar. Ultimately, these medications may help lower the risk of developing diabetes in people with arthritis.
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The relationship between diabetes and arthritis is multifaceted. While most of the time, their coexistence is due to genetics or common risk factors, studies show that diabetes can cause arthritis and arthritis can cause diabetes. More studies are currently being conducted on the topic, and we'll take good care of regularly keeping you updated on this article.