More than 422 million people worldwide suffer from “diabetes mellitus”. Unfavourable nutritional and lifestyle habits in particular have made diabetes a disease birthed by civilisation.

Diabetics have a pathological disorder involving their sugar metabolism. Their blood sugar levels are then permanently elevated. A distinction is made between type 1 diabetes mellitus and type 2 diabetes mellitus. While type 1 diabetes is relatively rare, about 95 out of 100 patients suffer from type 2.

There are also other types of diabetes:

  • LADA (latent autoimmune diabetes with adult onset) is a special form of type 1 diabetes, which often only develops in adulthood. The pancreas either does not produce enough insulin or does not produce any insulin at all.
  • In MODY (Maturity onset diabetes of the young) there is a genetic defect in the cells that produce the hormone insulin. Only about one percent of all diabetes patients are affected.
  • If the pancreas is damaged, this is known as pancreopriver diabetes. This damage can be caused by chronic alcohol abuse, gallstones or pancreatitis.
  • About 4 out of every 100 pregnant women develop gestational diabetes (gestational diabetes). However, this often recedes after the birth of the child.

Diabetes mellitus and its causes

Diabetes type 1 often manifests itself in adolescence. It is a chronic autoimmune disease in which the insulin-producing beta cells of the pancreas are destroyed, resulting in an insulin deficiency. Viral infections such as rubella or mumps as well as hereditary factors are also suspected of triggering the disease.

The cause of type 2 diabetes is a developed lack of effectiveness of insulin on cells. After eating food, the cells of the pancreas that have already become resistant do not react sufficiently or not at all, so that they do not release insulin. As a result, the blood sugar level rises sharply after food intake. The cells are no longer able to absorb glucose from the blood (insulin resistance).

Although the beta cells produce insulin which they release into the blood, the amount is not sufficient to lower the blood sugar level. This results in a so-called relative insulin deficiency, which the pancreas tries to compensate for at the beginning of the diabetes disease. As the disease progresses, however, the pancreas function decreases and the blood sugar level rises.

Cannabis use and diabetes

Cannabis use for recreational purposes was also considered a risk factor a few years ago. However, there is no scientific evidence of this as of yet.

US researchers had found in the CARDIA study, after interviewing cannabis users, that a large proportion of the respondents had developed pre-diabetes (1). Here, the blood sugar level is elevated, but still below the diabetes threshold. However, as the researchers could not find a direct link between cannabis use and pre-diabetes, they put forward the theory that pre-diabetes might have developed due to eating habits with calorie-containing food.

To date, there is little data on the relationship between cannabis and metabolic processes in the body. In 2013, US researchers had questioned a total of 4657 adults about their cannabis use and had taken blood samples to assess insulin resistance. Among the users, they found that they had lower levels of fasting insulin and insulin resistance in their blood than non-users (2).

On the other hand, a survey by US physicians showed that patients with type 1 diabetes who regularly used cannabis were twice as likely to suffer from diabetic ketoacidosis (3). Here, an absolute insulin deficiency occurs due to an excessive concentration of ketone bodies.

In the survey 450 patients were questioned, 124 of whom stated that they regularly used cannabis. 20.9 per cent of cannabis users had already been medically treated once for ketoacidosis. The rate among non-users was only 8.2 percent. However, the researchers admitted that it is unclear whether these results are representative.

Diabetes mellitus and its symptoms

Normally diabetes does not cause any symptoms in the beginning. The disease is usually discovered by chance, for example during a routine examination, or when consequential damage occurs. In the advanced stages, the following symptoms can occur:

  • severe thirst
  • ravenous appetite
  • lassitude
  • dry skin with itching
  • excessive urination
  • increased susceptibility to infections

In type 2 diabetes, the symptoms often first appear when 80 percent of the insulin-producing cells have been destroyed and the pancreas is no longer able to compensate for the insulin deficiency. Since the blood sugar level can rise very high, the patient is at risk of falling into a diabetic coma (diabetic ketoacidosis).

Consequential damages of a diabetes disease

Diabetes can trigger secondary diseases, especially if the blood sugar level is permanently elevated and not adjusted correctly. Other risk factors for secondary damage are an unhealthy diet and insufficient physical activity.

In diabetics it often happens that the blood vessels are damaged and a diabetic microangiopathy develops. This means that bleeding occurs, and the blood vessel walls become permeable. Thickening of the vessel walls can also lead to circulatory disorders and vascular occlusion. The retina of the eyes (diabetic retinopathy), the kidneys (diabetic nephropathy) and the feet (diabetic foot) are often particularly affected. In addition, patients often suffer from cardiovascular diseases.

Diagnosis and Diabetes Therapy

Diabetes mellitus is diagnosed by means of the blood sugar value. This is normally below 100 mg/dl in the blood plasma. After food intake, this value does not rise above 140 mg/dl.

Diabetes is present if the occasional blood sugar level is above 200 mg or 126 mg/dl when fasting. The same applies if the long-term blood sugar (HbA1c value) exceeds the value by more than 6.5 percent or the glucose tolerance test (oGTT 2-hour value) shows a value of more than 200 mg/dl.

The treatment depends on the type of diabetes the patient has. For type 1 diabetics it is vital to inject insulin regularly. Since antidiabetics are ineffective for this type of diabetes, short-acting insulin (insulin analogues) and long-acting normal insulin are used in the course of drug therapy.

For type 2 diabetics, on the other hand, several therapeutic options are available. It is particularly important here that the patient pays attention to his or her living and eating habits. A healthy diet and regular physical exercise should be on the agenda. Oral antidiabetics such as SGLT-2 inhibitors can be used as a supportive measure. If these drugs are not effective enough, insulin therapy is necessary.

What influence does medical cannabis have on diabetes?

In a placebo-controlled study, 62 diabetics (type 2) received different doses of cannabidiol (CBD) and tetrahydrocannabivarin (THCV) or a placebo (4) over a period of 13 weeks by researchers from the University of Nebraska. The THCV in particular showed a positive effect here. Compared to the placebo group, the cannabinoid reduced fasting plasma glucose and improved pancreatic cell function. The researchers concluded that THCV could be a potential agent for glycaemic control in diabetics.

Scientists at the University of Buckingham investigated the spectrum of action of THCV in obese mice (5). Again, THCV was shown to be able to reduce glucose intolerance. At the same time, glucose tolerance and insulin sensitivity improved in the mice.

Obesity is always associated with a risk of diabetes. But the links between obesity, diabetes and cannabis are still unclear. However, it is assumed that cannabis can influence body weight. Evidence is provided by a study by the Nelson Mandela Metropolitan University in South Africa, among others.

After administering a cannabis extract to overweight rats over a longer period of time, the researchers observed significant weight loss (6). The pancreas, however, gained weight. According to the researchers, the reason for this could be that the cannabinoids may have protected the beta cells responsible for insulin production by a mechanism that is still unknown.

Medical cannabis in diabetic neuropathy

Diabetic neuropathy or polyneuropathy, when several nerves are affected, is a common secondary disease of diabetes. Treatment is usually with drugs such as duloxetine, pregabalin or gabapentin to relieve the pain symptoms.

Cannabinoids, especially THC, can be a low side effect supplement to other pain therapy treatments. There are now also several studies that demonstrate the potential of cannabis in neuropathic pain (7).

In addition to THC, CBD also appears to have an analgesic effect. Researchers at the University of Milano-Bicocca studied this effect in rats with diabetic polyneuropathy (8). After the rats were repeatedly treated with CBD, the pain symptoms improved. Furthermore, CBD seemed to protect the liver from oxidative stress.

Conclusion

The scientific studies on diabetes and cannabis are not yet conclusive enough to conclude whether medical cannabis offers therapeutic benefits for diabetics. Although there is evidence that cannabinoids may improve insulin sensitivity and beta cell function so that patients with type 2 diabetes may benefit, this has not yet been clearly demonstrated.

Research is more advanced in the alleviation of neuropathic pain. Here there is clear evidence that medical cannabis can be a low side-effect supplement to conventional therapies.

(1) Department of Epidemiology and Community Health, School of Public Health, University of Minnesota, Minneapolis, USA, 2015, „Marijuana use and risk of prediabetes and diabetes by middle adulthood: the Coronary Artery Risk Development in Young Adults (CARDIA) study

(2) Creighton University, Elizabeth A Penner et al., 2013, „The impact of marijuana use on glucose, insulin, and insulin resistance among US adults

(3) ärzteblatt.de, Rüdiger Meyer, 2018, „Diabetes Typ 1: Cannabiskonsum könnte Ketoazidose fördern

(4) National Health Service, USA, Khalid A Jadoon et al., 2016, „Efficacy and Safety of Cannabidiol and Tetrahydrocannabivarin on Glycemic and Lipid Parameters in Patients With Type 2 Diabetes: A Randomized, Double-Blind, Placebo-Controlled, Parallel Group Pilot Study

(5) University of Buckingham, UK, E T Wargent et al., 2013, „The cannabinoid Δ9-tetrahydrocannabivarin (THCV) ameliorates insulin sensitivity in two mouse models of obesity

(6) Nelson Mandela Metropolitan University, Port Elizabeth, South Africa, Levendal RA1 et al., 2012, “Cannabis exposure associated with weight reduction and β-cell protection in an obese rat model

(7) Leafly.de, 2019, “Polyneuropathie und Cannabis als Medizin

(8) University of Milano-Bicocca, Milano, Italy, Comelli F1, 2009, ”Beneficial effects of a Cannabis sativa extract treatment on diabetes-induced neuropathy and oxidative stress