Diabetes mellitus is a disease in which the hormone insulin, which is responsible for regulating blood glucose (sugar) levels, does not work properly. Diabetes affects approximately 5% of people worldwide and can lead to serious complications such as cardiovascular disease, kidney disease, and foot and eye problems. The most frequent cases of diabetes fall into two categories. In type 1 diabetes, the pancreas does not produce enough insulin. In type 2 diabetes, the body does not use insulin properly.
Just like with heart disease, the majority of studies that have looked at the link between resveratrol and diabetes have been done in animals. Many rat studies have shown an association between resveratrol intake and improved blood glucose control. This may be due to resveratrol’s ability to protect the insulin-producing cells of the pancreas from damage and to improve glucose transport in muscle cells. Resveratrol may also reduce fat accumulation and inflammation in the liver, which are associated with diabetes. Fat deposits in the liver can lead to scar tissue buildup and eventually cirrhosis, in which the scarring significantly and irreversibly damages its function. As the liver is important to many key processes of the body, from toxin removal to the synthesis of vital proteins, liver failure is life threatening. Therefore, resveratrol’s potential ability to lessen complications of diabetes like cirrhosis is extremely valuable.
The role of inflammation
There have also been data to suggest that resveratrol may help to fight chronic inflammation in fat tissue. This is important because both obesity and inflammation are associated with type 2 diabetes. With more than two thirds of adults in the United States overweight or obese, this has important potential clinical applications. Inflammation can be a confusing topic, so let’s go back to the definitions for a minute. Inflammation is a biological process by which the body produces an immune response to combat undesirable events such as injury or invasion by a pathogen. Although inflammation can sometimes be uncomfortable (think about the redness and swelling that happens when you cut yourself), it’s the body’s way of sending healing help to the site.
The problem happens when inflammation doesn’t go away. Although it’s not fully understood how inflammation becomes chronic, fat tissue may play a large role. When fat cells (also known as adipocytes) are forced to store excess nutrients, this can trigger a state of chronic low-grade inflammation. This inflammation can disrupt normal processes in the body, such as the action of insulin, thus leading to chronic diseases such as diabetes. By acting as an anti-inflammatory agent (the exact mechanisms are still not fully understood, but researchers have illuminated several key biological targets), resveratrol may help to lighten the burden of chronic disease.
Human clinical trials
As with heart disease, there is limited human data on the link between resveratrol and diabetes. In the last six years researchers have begun to study it more intensively in human clinical trials. The results are mixed, with some trials showing no significant results, but there have been some important developments. Short-term resveratrol supplementation with doses of as little as 10 mg/day for 4 weeks has been shown to improve insulin resistance in patients with type 2 diabetes, whereas use of larger doses (250 mg/day for 3 months and 1000 mg/day for 45 days) has been shown to lower blood glucose levels. These findings are encouraging, but the studies do have limitations that are important to take into account. For example, since the study subjects were type 2 diabetics, all of them were already on a glucose-lowering medication. Very high blood glucose can be extremely dangerous, so it would be unethical if they weren’t. Although significant differences were still seen between the groups that received resveratrol and the ones that didn’t, it’s important to consider potential interactions between resveratrol and medications and control for them carefully. This is part of what makes human clinical trials so difficult and why so much more research has been done with animals. The range of doses of resveratrol used in these studies is also interesting. If as little as 10 mg/day can produce a clinical effect, people may be much more comfortable taking this amount as a supplement than higher doses. The investigators in the study using 1000 mg/day acknowledged that rigorous toxicological screening had not been done on their subjects to ensure that the dose was safe long-term. As researchers learn from each other’s mistakes and the library of evidence expands, we will continue to elucidate resveratrol’s potential role as a treatment for diabetes.
References
Bhatt, Jayesh Kumar, Sabin Thomas, and Moola Joghee Nanjan. “Resveratrol supplementation improves glycemic control in type 2 diabetes mellitus.” Nutrition Research 32.7 (2012): 537-541.
DeBoer, Mark D. “Obesity, systemic inflammation, and increased risk for cardiovascular disease and diabetes among adolescents: a need for screening tools to target interventions.” Nutrition 29.2 (2013): 379-386.
Donath, Marc Y. “Targeting inflammation in the treatment of type 2 diabetes: time to start.” Nature Reviews Drug Discovery 13.6 (2014): 465-476.
Movahed, Ali, et al. “Antihyperglycemic effects of short term resveratrol supplementation in type 2 diabetic patients.” Evidence-Based Complementary and Alternative Medicine (2013).
Nelms, Marcia, et al. Nutrition Therapy & Pathophysiology. 2nd ed., Cengage Learning, Inc., 2010.
Poulsen, Morten Møller, et al. “Resveratrol and inflammation: Challenges in translating pre-clinical findings to improved patient outcomes.” Biochimica et Biophysica Acta (BBA)-Molecular Basis of Disease 1852.6 (2015): 1124-1136.
Szkudelski, Tomasz, and Katarzyna Szkudelska. “Resveratrol and diabetes: From animal to human studies.” Biochimica et Biophysica Acta (BBA)-Molecular Basis of Disease 1852.6 (2015): 1145-1154.