From the Cannabis Medical Dictionary CannabisMD.net

Diabetes is a condition wherein the body either produces inadequate amounts of insulin or fails to utilize available insulin properly. An estimated 1 million Americans suffer from Type 1 diabetes, which develops in childhood. Another 15 million suffer from Type 2 diabetes, also known as adult onset diabetes, which develops later in life.Symptoms generally include an imbalance of blood sugar levels and a high level of sugar excreted through the urine. Initial studies showed that cannabis has no effect on blood sugar levels. A recent test-tube study showed that very high doses of synthetic THC might aggravate diabetes, but that same research also indicates that continued use of cannabis creates a tolerance to the potential aggravation . No human studies have found that cannabis or synthetic cannabinoids contribute to symptoms of diabetes. At the same time, no human studies have been undertaken to prove or disprove the reports of long-term diabetics who claim that cannabis use causes an immediate lowering of abnormally high blood sugar levels .Some diabetics also claim that cannabis helps stabilize blood sugar levels and maintain mental stability, or correct mood swings caused by fluctuating blood sugar levels .Separating the apparent blood sugar response from the anti-anorexic properties of cannabis is currently a matter for further investigation.

Diabetics are frequently instructed to refrain from alcohol use because of its high caloric content. Cannabis may provide a psychologically valuable alternative to alcohol in stress reduction, a major factor in managing the potentially life threatening symptoms of diabetes. Hence, cannabis may function in several ways to reduce and stabilize blood sugar levels for patients suffering from diabetes. However, regardless of mounting anecdotal evidence in medical practice, including medical testimony before a district court in California .No scientific papers have been published on the effectiveness of cannabis in treating diabetes.

While cannabis has been used as a replacement for insulin, diabetics are strongly advised to continue their physician’s prescribed treatment plan.