Short answer
No large trial shows that cannabis lowers blood sugar in people with diabetes. Survey data link cannabis use to lower fasting insulin and lower insulin resistance, but those findings do not prove cause. Cannabis can move glucose up or down in the short term depending on dose, product, and the person. It is not a diabetes treatment.
cannabis effects on insulin resistance
What observational studies found
Several analyses of NHANES, a US national health survey, compared cannabis users with non-users.
- Current users had lower fasting insulin and lower HOMA-IR, a measure of insulin resistance, than people who never used.
- Fasting glucose and A1c differed little between groups in most of those analyses.
- Users in the same datasets had smaller waist circumference on average.
These are cross-sectional snapshots. People who use cannabis may differ from non-users in diet, activity, and income. The datasets cannot separate THC from CBD, or smoked flower from edibles.
Clinical trial data
A 2016 randomized pilot trial at the University of Nottingham gave 62 adults with type 2 diabetes CBD or tetrahydrocannabivarin (THCV) for 13 weeks. THCV at 5 mg twice daily lowered fasting plasma glucose and improved a marker of beta-cell function. The 100 mg THCV dose did not. CBD at 100 mg twice daily changed resistin and GIP, two hormones tied to insulin action, but did not lower glucose. The trial was small and short. No regulatory body has approved CBD or THCV for glycemic control.
Cannabis Effects on Insulin Resistance: A Comprehensive Guide
Risks for people with diabetes
- Type 1 diabetes: a Colorado study of adults with type 1 diabetes found cannabis users had more than twice the rate of diabetic ketoacidosis events compared with non-users.
- Symptom overlap: THC can cause dry mouth, hunger, fast heartbeat, and dizziness. Those signs also appear with hypoglycemia. A person may misread low blood sugar as a cannabis effect.
- Inhaled cannabis raises heart rate for 1 to 3 hours. Diabetes already raises cardiovascular risk.
- Cannabinoid hyperemesis syndrome causes repeated vomiting. Vomiting plus diabetes can push glucose and electrolytes out of range.
Drug interactions
CBD inhibits CYP3A4, CYP2C19, and CYP2D6 in lab and human studies. Those enzymes break down some diabetes drugs and many other prescriptions. Metformin does not travel that route. Sulfonylureas such as glipizide and some statins do. Anyone on insulin or a sulfonylurea faces a higher chance of low blood sugar when appetite or eating changes.
Edibles and sugar
Gummies, chocolates, and drinks carry 2 to 15 grams of sugar per dose in many products. Labels list total carbohydrate. A 10 mg dose can come with the same sugar as half a can of soda. Inhaled products carry no sugar.
What to track
- Check glucose before and 2 hours after a new product.
- Keep a note of product type, THC and CBD milligrams, and route.
- Tell your clinician about cannabis use at each visit.
- Treat suspected lows with 15 grams of fast carbohydrate, then retest in 15 minutes.
Unknowns
No long-term randomized trial has tested smoked cannabis against placebo in people with diabetes. Dose, route, and the ratio of THC to CBD vary across products, so results from one product do not carry to another. Federal law limits cannabis research in the US.