CBD and insulin glargine (e.g. Lantus, Optisulin)

CBD oil has attracted considerable attention in recent years. If you are thinking about using CBD as a supplement while also taking insulin glargine (e.g. Lantus, Toujeo, Abasaglar, Semglee), it is important to be aware of potential interactions between CBD and your diabetes treatment.

• Direct pharmacokinetic interactions between CBD and insulin glargine are considered unlikely (glargine is not metabolised via CYP enzymes).
• More relevant is the pharmacodynamics: CBD may influence your blood glucose or eating patterns – this could increase the risk of low blood sugar (hypoglycaemia).
• Start with a low CBD dose, monitor your glucose (capillary or CGM) closely for 1–2 weeks and keep a record of readings, doses and symptoms.
• Never stop insulin on your own initiative. Discuss any changes with your diabetes care team, especially in the case of type 1 diabetes.
• Take particular care if you have a history of hypos, liver disease, take multiple medicines, or are older.

What is CBD and how does it work in the body?

CBD is a non-intoxicating compound derived from the cannabis plant. It interacts with the endocannabinoid system, which is involved in modulating processes such as sleep, mood, how pain is perceived and inflammatory responses.

Read more here about how CBD is discussed in relation to the body

Insulin glargine in brief

Insulin glargine is a long-acting basal insulin used in type 1 and type 2 diabetes. Branded preparations include Lantus (U100), Toujeo (U300), Abasaglar and Semglee. After subcutaneous injection, glargine is released slowly and broken down proteolytically into active metabolites; CYP-dependent liver metabolism is not a relevant pathway.

CBD and insulin glargine interactions

Pharmacokinetics: CBD metabolism vs insulin glargine

CBD may inhibit certain liver enzymes (especially CYP3A4/2C19) and thereby influence how some prescription medicines are broken down. These potential CBD drug interactions are mainly linked with hepatic CYP metabolism.

For insulin glargine this is of little relevance: as a peptide hormone, glargine is degraded proteolytically and not via CYP enzymes. A direct pharmacokinetic interaction between CBD and insulin glargine is therefore considered unlikely.

For other concomitant medicines the situation may be different – it can be useful to look at general CBD interactions and how CBD affects liver enzymes and CYP3A4.

Pharmacodynamics: Blood glucose, insulin sensitivity, appetite

Findings from preclinical work and small human studies suggest that cannabinoids (including CBD) may be involved in processes related to glucose metabolism, appetite and sleep. The evidence is heterogeneous and effects appear to vary between individuals.

In practical terms, when CBD is used together with insulin glargine:

• CBD-associated changes in apparent insulin sensitivity could increase the risk of hypoglycaemia if your basal insulin dose is not reviewed by a healthcare professional.
• Changes in eating behaviour (for example, reduced appetite or irregular meals) can also contribute to hypos – particularly if the basal insulin dose remains unchanged.
• Possible tiredness while using CBD may make it harder to notice early warning signs of a hypo.

Who may be particularly vulnerable?

• People with type 1 diabetes (risk of diabetic ketoacidosis with insufficient insulin; CBD does not replace insulin)
• History of frequent or severe hypos
• Liver disease, older age, underweight
• Use of several medicines (polypharmacy), especially other medicines linked with hypo risk or central nervous system depression

You can also check potential individual interactions with our tool and discuss the results with your doctor.

Practical guidance if you are considering CBD with insulin glargine

Monitoring plan for the first 1–2 weeks

• Measure blood glucose more frequently: fasting, before and after meals, and before bed; review CGM trends daily if you use one.
• Keep a log: time and dose of CBD, time and dose of insulin glargine, meals/carbohydrate portions, exercise, and any symptoms (e.g. hypos, dizziness, nausea, tiredness).
• Set alarm thresholds: activate CGM alarms for low readings (for example 80–90 mg/dl; 4.4–5.0 mmol/l) where possible.
• Do not adjust basal insulin doses on your own: only change insulin glargine after consulting your diabetes care team.
• Seek medical advice promptly if you have repeated readings <70 mg/dl, unexplained night-time hypos, ketones or feeling unwell (especially with type 1 diabetes).

“Possible effects & what to do”

Hypoglycaemia: Warning signs & immediate actions

• Typical signs: shaking, sweating, palpitations, hunger, difficulty concentrating, irritability, drowsiness or feeling confused.
• Immediate action: 15 g fast-acting carbohydrates (e.g. 3–4 glucose tablets, 150 ml juice), recheck after 15 minutes and repeat if needed.
• If unconscious or unable to swallow: call emergency services; use glucagon according to your treatment plan.

Points to note for type 1 vs type 2 diabetes

• Type 1 diabetes: CBD never replaces insulin. Insufficient insulin can lead to ketoacidosis. Only adjust basal insulin with medical guidance.
• Type 2 diabetes: in some individuals, CBD use may coincide with changes in insulin needs. Focus on monitoring, planned dose reviews and communication with your diabetes team.

Forms of CBD use and dosing considerations

• “Start low, go slow”: begin with a low CBD dose and increase gradually in multi-day steps if needed, while tracking your blood glucose.
• Onset of effects ranges from minutes to hours (vapes faster, oils/capsules slower), with overall assessment usually over days or weeks.

Talking to your doctor: Questions that can help

• Should I monitor my basal insulin glargine dose particularly closely over the next 1–2 weeks if I start CBD?
• Which thresholds or patterns in my readings would suggest that a dose adjustment is needed?
• How should I manage night-time hypos if I am using CBD?
• Are there any CBD interactions to consider with my other prescription medicines?

Keeping an eye on CBD product quality

• Check certificates of analysis (COA) for cannabinoid profile, THC content and contaminants such as heavy metals and pesticides.
• Favour products from manufacturers with transparent information and reproducible dosing.
• Avoid combining CBD with alcohol or strongly sedating substances.

Important information

While insulin glargine is not broken down by CYP enzymes, CBD may be associated with changes in blood glucose in some individuals. The main concern in this context is low blood sugar, particularly in the first weeks of use. Never stop insulin without medical advice. If you are pregnant or breastfeeding, have liver disease or take several long-term medicines, only use CBD after consulting a healthcare professional.

Side effects and precautions

CBD

CBD is generally regarded as well tolerated. Commonly reported, mostly mild, side effects include sleepiness, dry mouth, dizziness, a drop in blood pressure and, less commonly, nausea/diarrhoea or changes in appetite. CBD may increase liver enzymes (ALT/AST) and can have additive effects with centrally sedating substances. If you have existing liver disease, are pregnant or breastfeeding, or take multiple medicines, it is advisable to speak to your doctor.

CBD overdose: What is known?

Insulin glargine

The most important side effect is hypoglycaemia (e.g. sweating, trembling, palpitations, confusion). Local reactions (redness, swelling) can occur, as well as rare allergic reactions.

Conclusion

Direct pharmacokinetic interactions between CBD and insulin glargine are considered unlikely, as glargine is not metabolised by CYP liver enzymes. In practice, the key consideration is the possibility of changes in your blood glucose and a resulting higher risk of hypoglycaemia, especially in the first weeks after starting CBD. A structured approach can help: low initial CBD dosage, close monitoring (capillary or CGM), a clear plan for dealing with hypos, and prompt contact with your diabetes care team if anything unusual occurs.

Disclaimer: This article is for information purposes only and does not replace medical advice. Do not change medicines or dosages without consulting your doctor. No claims are made regarding the treatment or cure of illnesses.