Diabetes mellitus (also known as primary diabetes) affects approximately 8.3% of the US population and 6.8% of Canadians. In 2007, diabetes contributed to over 200,000 deaths in the US alone.
Although the early development of insulin medications made diabetes treatable, no cure exists and symptoms tend to worsen as the disease progresses.
Now, a growing body of evidence points to medical marijuana as a promising therapy. In fact, research shows that marijuana may not only be useful for managing symptoms of pain and cardiovascular disease, but also aid in combating the disease itself.
What is Diabetes?
Diabetes mellitus is a group of metabolic diseases characterized by high blood glucose levels. The two most common forms of diabetes are known as Type 1 and Type 2 diabetes.
Type 1 diabetes is usually diagnosed in individuals under the age of 30 and involves an autoimmune attack on islet cells of the pancreas – cells that produce insulin. Approximately 10% of diabetics suffer from Type 1 diabetes.
Type 2 diabetes is far more common and tends to affect individuals that are obese and over the age of 40. It is usually a result of a combination of defective insulin production and insulin resistance.
In both types of diabetes, high blood sugar levels eventually lead to a variety of other metabolic and non-metabolic complications.
Endocannabinoids and Diabetes
Endocannabinoids are natural compounds found within all humans that happen to act in a similar way as plant-derived cannabinoids such as THC. Along with cannabinoid receptors, they make up what is known as the endocannabinoid system.
Cannabinoid receptors have been identified in the pancreas, heart, blood vessels, nervous system and many other organs – all of which suggests a potential role for cannabinoids in treating diabetes.
Interestingly, large-scale surveys have found lower prevalence rates of obesity and diabetes mellitus among marijuana users compared with non-users, suggesting the potential for cannabinoids to affect this disorder.
Studies have also identified higher endocannabinoid levels (anandamide and 2-AG) in diabetic patients compared to healthy individuals.
Marijuana and Insulin
Insulin dysfunction is the underlying factor in diabetes as well as the primary target of medical treatment. Interestingly, the presence of cannabinoid receptors has been identified in cells of the pancreas that produce insulin.
Studies involving human cell cultures have linked activation of CB1 receptors to an increase in insulin production. On the other hand, the role of CB2 receptors is conflicted, with some studies showing an increase in insulin secretion and others showing a decrease.
Marijuana compounds may take on another therapeutic role in type 1 diabetes by regulating activity of the immune system. In an animal model of type 1 diabetes, THC demonstrated an incredible ability to counter autoimmune attacks. THC treatment was also able to preserve insulin levels and lower blood glucose levels compared with the untreated group.
Other studies have found CBD (cannabidiol) and THCV (tetrahydrocannabivarin) – two non-psychoactive compounds found in marijuana – to have similar protective effects.
A study published in 2006 found that CBD could reduce the chance of developing type 1 diabetes in mice by reducing inflammation of pancreatic cells. In a study involving obese mice, THCV treatment led to improved glucose tolerance, reduced glucose intolerance and increased insulin sensitivity, leading the authors to conclude that THCV could be a useful therapy for type 2 diabetes either alone or together with CBD.
“Based on these data, it can be suggested that THCV may be useful for the treatment of the metabolic syndrome and/or type 2 diabetes, either alone or in combination with existing treatments… a CBD/THCV combination may be beneficial for different types of diabetes mellitus.”
Excerpt from The cannabinoid Δ9-tetrahydrocannabivarin (THCV) ameliorates insulin sensitivity in two mouse models of obesity (Wargent et al., 2013)
Finally, a large-scale observational study published in 2013 by Harvard University researchers found that adults who used marijuana had lower fasting insulin levels and a lower probability of being insulin resistant. The study collected data from over 4,500 adults during a 5 year period.
Marijuana and Obesity
Type 2 diabetes is commonly associated with obesity and related cardiovascular problems. Interestingly, the endocannabinoid system appears to be involved with obesity and regulating energy balance as well.
Early studies revealed higher levels of the endocannabinoids anandamide and 2-AG in obese individuals, which led experts believed that activity of the endocannabinoid system promoted obesity. Along the same line, activity of the endocannabinoid system has been shown to decrease energy expenditure and increase food intake and fat storage.
However, more recent evidence suggests an opposite effect on obesity.
In the same Harvard University study, researchers found that marijuana users had lower waist circumferences, despite the fact that they tended to consume more calories. Similarly, a 2011 analysis of 2 large U.S. surveys linked marijuana use with a lower BMI and a decreased prevalence of obesity.
Marijuana and Cardiovascular Disease
Recent studies also suggest a therapeutic role of cannabinoids in a number of cardiovascular complications that accompany diabetes. As it turns out, CB1 and CB2 receptors are expressed in various cells of the cardiovascular system, including the immune cells that infiltrate them.
In mouse models, cannabinoids have demonstrated the ability to regulate vascular inflammation, oxidative stress and atherosclerosis, leading experts to suggest that marijuana-based medications may be useful in the treatment of these dysfunctions.
“Modulation of the endocannabinoid system… may hold tremendous therapeutic potential in various cardiovascular disorders associated with inflammation and tissue injury, ranging from myocardial infarction and heart failure to atherosclerosis and cardiometabolic disorders.”
Excerpt from The emerging role of the endocannabinoid system in cardiovascular disease (Pacher and Steffens, 2009)
Marijuana and Neuropathic Pain
Approximately 60-70% of diabetics suffer from some form of nerve damage, which can often lead to a specific type of pain known as neuropathic pain.
Interestingly, neuropathic pain has been one of the few applications of medical marijuana to be investigated in clinical trials. Sativex – a cannabis-derived oral spray – has already been approved by countries such as Canada and the United Kingdom for the treatment of pain associated with cancer and multiple sclerosis.
While yet to be approved for diabetics, cannabis-based treatments have also shown promise in clinical trials involving diabetes-related neuropathic pain.
A placebo-controlled clinical trial published in 2012 found that 85% of patients given synthetic THC (Cesamet) experienced a reduction in pain of at least 30%. Furthermore, all patients that received the strongest dose (4mg/day) experienced a reduction in pain of 30% or more. The study also identified significant improvements in overall disease scores. Side-effects were relatively minor and included confusion, drowsiness and dizziness.
Finally, other studies show that cannabis use can lead to improvements in sleep, mood and quality of life in patients with neuropathic pain.