Drug & supplement interaction

Bilberry + Insulin Glargine

Insulin Glargine brand names: Basaglar, Lusduna, Semglee.

Moderate Interaction
Medically reviewed by · Updated September 2026
The bottom line Moderate

Bilberry has a moderate interaction with Insulin Glargine. Theoretically, bilberry leaf or fruit extract may increase the risk of hypoglycemia when taken with antidiabetes drugs.

Read the full interaction report
SeverityModerate
LikelihoodPossible
EvidenceD
What do Severity, Likelihood & Evidence mean?
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Interaction report

Bilberry and Insulin Glargine

Here is the interaction we found between these two, with the evidence behind it.

Moderate

ANTIDIABETES DRUGS

Why this applies to Insulin Glargine

Insulin Glargine falls under ANTIDIABETES DRUGS — the group Bilberry interacts with.

Theoretically, bilberry leaf or fruit extract may increase the risk of hypoglycemia when taken with antidiabetes drugs.
Animal research suggests that bilberry leaf extract might have blood glucose-lowering activity. Also, one small clinical trial in patients with type 2 diabetes shows that taking bilberry fruit extract 470 mg as a single dose prior to an oral glucose tolerance test lowers plasma glucose levels when compared with placebo.
Severity Moderate Likelihood Possible Evidence D

Interaction has been documented in animal or in lab research, or the interaction has been documented in humans but is limited to case reports or conflicting clinical research exists.

Dr. Brian Staiger, PharmD, BCPS
Dr. Brian Staiger explains PharmD, Clinical Pharmacist

Here's the simple version: bilberry, especially concentrated extracts of the leaf or fruit, may have a mild blood-sugar-lowering effect of its own. Since insulin glargine (Basaglar, Semglee, Lusduna) is already working hard to bring your glucose down, stacking the two could push your levels a little lower than expected. That raises the chance of hypoglycemia, with signs like shakiness, sweating, dizziness, a racing heart, or feeling foggy and weak.

I want to keep this in perspective, though. The evidence here is weak, coming mostly from animal studies and one small human test, so this is more theoretical than proven. Eating bilberries as food is unlikely to be a problem. If you want to try concentrated supplements, check in with your pharmacist or doctor first, and keep an eye on your sugar readings.

Contact Dr. Brian directly if you have additional questions on this interaction
References
  1. Cignarella A, Nastasi M, Cavalli E, Puglisi L. Novel lipid-lowering properties of Vaccinium myrtillus L. leaves, a traditional antidiabetic treatment, in several models of rat dyslipidaemia: a comparison with ciprofibrate. Thromb Res 1996;84:311-22. PubMed
  2. Hoggard N, Cruickshank M, Moar KM, Bestwick C, Holst J, Russell W, et al. A single supplement of a standardized bilberry (Vaccinium myrtillus L.) extract (36% wet weight anthocyanins) modifies glycaemic response in individuals with type 2 diabetes control

What These Ratings Mean

Every interaction above is graded three ways — here’s the key to each label.

Severity how clinically significant the interaction is
Major

Clinically significant. Avoid the combination, or use only under close professional supervision.

Moderate

Usually worth avoiding or managing — may need monitoring, a dose change, or timing apart.

Minor

Generally not serious. Be aware of it and mention it to your pharmacist.

Likelihood how strong the evidence is that the interaction actually happens in people
  • LikelyWell-controlled human studies have demonstrated the likely existence of this interaction.
  • ProbableInteraction has not been documented in well-controlled studies, however, the interaction has been demonstrated in some small human studies or in controlled animal studies in conjunction with multiple case reports.
  • PossibleInteraction has been documented in animal or in lab research, or the interaction has been documented in humans but is limited to case reports or conflicting clinical research exists.
  • UnlikelyInteraction has been demonstrated in animal or in lab research but has been shown not to occur in humans.
Evidence the quality of the studies behind the rating (graded A–D)
  • AHigh-quality meta-analysis (quantitative systematic review).
  • BCase-control study.
  • CConsensus.
  • DAnecdotal evidence.

These ratings are for information only. Never start, stop, or otherwise change your therapy before speaking with your provider.

Keep it in perspective

Bilberry Also Interacts With Other Medications

Bilberry has 274 moderate known drug interactions in our database — the Insulin Glargine one above is one of them. If you take anything else, check it against the full list below.

Moderate 274 No known interaction 2,556 (incl. Insulin Glargine)
Taking anything else?

Check Another of Your Medications Against Bilberry

Covers the 2,830 medications we’ve checked against Bilberry. Pick one to open its full report.

Everything else you take

See Every Supplement That Interacts With Insulin Glargine

This page covers Bilberry only. If you take other supplements — a multivitamin, a sleep aid, something for joints — the Insulin Glargine page lists 242 supplements it has a documented interaction with, worst first, each one explained.

The most serious there right now: Chelation Therapy Products (major), Siberian Cocklebur (major), Acai (moderate), African Wild Potato (moderate) and Agaricus Mushroom (moderate).

By severity: 2 major · 211 moderate · 29 minor.

Open the Insulin Glargine interaction page

One more smart check

Taking Bilberry as Part of a Dietary Supplement Product? Check It for Interactions

We hold 3,883 real supplement products containing Bilberry, each one broken down to its full ingredient list — and combination products often carry several ingredients besides Bilberry. Your product may carry other ingredients that interact with Insulin Glargine too, on top of Bilberry — and those would not show on this page. Find your product and we’ll check every ingredient on its label:

How much people look this up

Where Bilberry and Insulin Glargine Sit Against Everything Else

Out of every supplement and medication people look up on HelloPharmacist, here is where these two land this week — and which way each has been moving.

Supplement Bilberry
Top 10%

#84 of 1,452 supplements looked up here in the last 7 days

29 days ago today
Medication Insulin Glargine
Top half

#1,394 of 2,830 medications looked up here in the last 7 days

29 days ago today

Position among everything looked up on this site, not a measure of how commonly either one is used or how important it is. A supplement can climb this list because of a news story. It counts every request to the page, automated ones included, and nothing here identifies anyone.

Supplement

About Bilberry

What is Bilberry?

Bilberry
  • Eye and vision health
  • Antioxidant support
  • Diarrhea and digestive upset
  • Circulation and vein health
  • Blood sugar support

Bilberry is a blueberry-like fruit rich in antioxidant plant compounds called anthocyanins, and it has a long history of traditional use for eye health, circulation, and mild diarrhea. While it is generally well tolerated as a food and supplement, strong scientific proof for most health claims is limited. Talk with your pharmacist or doctor before using bilberry supplements, especially if you are pregnant, breastfeeding, or have a health condition.

Read the full Bilberry monograph & all interactions
Medication

About Insulin Glargine (rDNA origin) Injection

What Is Insulin Glargine (rDNA origin) Injection Used For?

Brand names: Basaglar, Lusduna, Semglee

Insulin glargine is used to improve glycemic control (blood sugar management) in adults and pediatric patients with type 1 diabetes mellitus, and in adults with type 2 diabetes mellitus. It is a long-acting basal insulin, meaning it works gradually over the course of the day to keep blood sugar steady.

Insulin glargine is not recommended for treating diabetic ketoacidosis (a serious complication where the blood becomes dangerously acidic).

See full Insulin Glargine (rDNA origin) Injection drug information
Keep checking

Other Drugs & Bilberry

Browse every other medication we’ve checked against Bilberry — both the ones with a known interaction and the ones without. Select any drug for the full detail.

0Major
274Moderate
0Minor
2,555No known interaction
274 Moderate 2,555 No interaction
Moderate

274 interactions

Showing 60 of 274 moderate interactions — see all 274 on the Bilberry page.

No interaction 2,555 drugs checked — show the list

We also checked Bilberry against these medications and found no known interaction in our sources. Open any page to confirm.

Showing the 60 most looked-up of 2,555 medications checked with no known interaction — see the full Bilberry list.

See the full Bilberry interactions page
See every supplement checked against Insulin Glargine, ranked by severity
Sources

Sources & How We Checked

Interaction details are evidence-graded and sourced from the Natural Medicines database. The medication overview comes from MedlinePlus.

Content is written and reviewed by licensed HelloPharmacist pharmacists. See our data sources and editorial standards for how this information is built and checked.

Parts of this content are provided by the Therapeutic Research Center, LLC.

DISCLAIMER: Currently this does not check for drug-drug interactions. This is not an all-inclusive comprehensive list of potential interactions and is for informational purposes only. Not all interactions are known or well-reported in the scientific literature, and new interactions are continually being reported. Input is needed from a qualified healthcare provider including a pharmacist before starting any therapy. Application of clinical judgment is necessary.

© 2021 Therapeutic Research Center, LLC

Keep exploring
Bilberry monograph › Uses, safety, and every drug interaction in one place Insulin Glargine supplement interactions › Every supplement checked against Insulin Glargine, ranked by severity Insulin Glargine (rDNA origin) Injection drug information › The full plain-English guide to this medication Supplement interaction checker › Check any supplement or product against your medications Browse medications A–Z › Every drug we've checked against herbs & supplements Ask a pharmacist › Free, personal answer from our licensed team
Pharmacist Counseling Corner

Taking Bilberry and Insulin Glargine Together: Common Questions

Can you take Bilberry with Insulin Glargine?
There is a moderate interaction, so it may be acceptable with monitoring or timing changes — but check with your pharmacist first. Read the full details on this page and confirm with your pharmacist before combining them.
How serious is the Bilberry and Insulin Glargine interaction?
We rate it Moderate. This combination may require monitoring, a dose adjustment, or separating the times you take each one. Consult your pharmacist before using them together.

Written and reviewed by the HelloPharmacist editorial staff. Our editorial policy

Still Have a Question About Insulin Glargine and Bilberry?

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This information is for education only and is not a substitute for professional medical advice. Always check with your pharmacist or doctor before starting, stopping, or combining supplements and medications.