Drug & supplement interaction

Fasting + Insulin (Human)

Insulin (Human) brand names: Novolin N, Novolin 70/30, Novolin R, Novolin L, Afrezza.

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

Insulin (Human) falls into 2 drug categories that Fasting can interact with; the most serious is rated moderate. Fasting might increase the risk of hypoglycemia if used with antidiabetes drugs.

Read the full interaction report
SeverityModerate
LikelihoodPossible
Interactions2
EvidenceB
What do Severity, Likelihood & Evidence mean?
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Interaction report

Fasting and Insulin (Human)

These two interact in 2 distinct ways. Each one is explained separately below.

Why Are There 2 Interactions?

Fasting interacts with whole categories of medication. Insulin (Human) falls into 2 of those categories, so it can interact with Fasting in 2 different ways. We’ve listed each one below — your overall risk is driven by the most serious of them (Moderate).

Moderate

ANTIDIABETES DRUGS

1 of 2

Why this applies to Insulin (Human)

Insulin (Human) falls under ANTIDIABETES DRUGS — the group Fasting interacts with.

Fasting might increase the risk of hypoglycemia if used with antidiabetes drugs.
Hypoglycemic events have been reported during intermittent fasting, including in patients using antidiabetes drugs. The risk of having a hypoglycemic event is largest for patients taking insulin or sulfonylureas. The risk of hypoglycemic events seems to be lower for patients taking other antidiabetes drugs such as glucagon-like peptide-1 receptor agonist (GLP- 1RA), metformin, thiazolidinediones, dipeptidyl peptidase-4 inhibitors (DPP4 inhibitors), and sodium-glucose cotransporter-2 (SGLT2) inhibitors. Advise patients to monitor glucose levels closely. Dose or time adjustments may be necessary.
Severity Moderate Likelihood Possible Evidence B

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 thing to keep in mind: insulin's whole job is to lower your blood sugar by moving it out of your blood and into your cells. When you fast, you're not taking in food to push that sugar back up. Put those two together and your blood sugar can drop too low, which we call hypoglycemia. With insulin, this is one of the bigger risks compared to many other diabetes drugs.

Low blood sugar can make you feel shaky, sweaty, dizzy, confused, or very hungry, and if it falls far enough it can be dangerous. The evidence here is moderate, not rock solid, but it's real and worth respecting. Please don't stop or change your insulin on your own. If you're thinking about fasting, talk with your doctor or pharmacist first. Your dose or timing may need adjusting, and checking your glucose often is key.

Contact Dr. Brian directly if you have additional questions on this interaction
References
  1. Carter S, Clifton PM, Keogh JB. Effect of intermittent compared with continuous energy restricted diet on glycemic control in patients with Type 2 diabetes: A randomized noninferiority trial. JAMA Netw Open. 2018;1(3):e180756. PubMed
  2. Cioffi I, Evangelista A, Ponzo V, et al. Intermittent versus continuous energy restriction on weight loss and cardiometabolic outcomes: a systematic review and meta-analysis of randomized controlled trials. J Transl Med. 2018;16(1):371. PubMed
  3. Chowdhury A, Khan H, Lasker SS, Chowdhury TA. Fasting outcomes in people with diabetes and chronic kidney disease in East London during Ramadan 2018: The East London diabetes in Ramadan survey. Diabetes Res Clin Pract. 2019;152:166-170. PubMed
  4. Grajower MM, Horne BD. Clinical management of intermittent fasting in patients with diabetes mellitus. Nutrients. 2019;11(4):873. PubMed
  5. Ibrahim M, Davies MJ, Ahmad E, et al. Recommendations for management of diabetes during Ramadan: update 2020, applying the principles of the ADA/EASD consensus. BMJ Open Diabetes Res Care. 2020;8(1):e001248. PubMed
  6. Wang X, Li Q, Liu Y, Jiang H, Chen W. Intermittent fasting versus continuous energy-restricted diet for patients with type 2 diabetes mellitus and metabolic syndrome for glycemic control: A systematic review and meta-analysis of randomized controlled tria
Moderate

INSULIN

2 of 2
Fasting might increase the risk of hypoglycemia if used with insulin.
Hypoglycemic events have been reported during intermittent fasting. The risk of a hypoglycemic event seems to be highest in patients using insulin or sulfonylureas. Patients with type 2 diabetes and other comorbidities, or those with type 1 diabetes, should be strongly advised to avoid fasting while taking insulin. For patients taking insulin who insist on fasting, advise these patients to monitor glucose levels closely. Dose or time adjustments may be necessary.
Severity Moderate Likelihood Probable Evidence B

Interaction 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..

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

Here's the thing to keep in mind: insulin lowers your blood sugar, and so does going without food. When you stack the two together, you can push your sugar down too far. That's hypoglycemia, and with insulin it's a real concern, not just a theoretical one.

If your blood sugar drops too low, you might feel shaky, sweaty, dizzy, confused, or irritable, and in serious cases it can lead to passing out. Because your insulin dose is usually matched to the food you eat, skipping meals while keeping the same dose tilts the balance toward a low. Please don't start fasting, or change your insulin, on your own. Talk with your doctor or pharmacist first. If they're okay with it, they may adjust your dose or timing and have you check your glucose more often.

Contact Dr. Brian directly if you have additional questions on this interaction
References
  1. Carter S, Clifton PM, Keogh JB. Effect of intermittent compared with continuous energy restricted diet on glycemic control in patients with Type 2 diabetes: A randomized noninferiority trial. JAMA Netw Open. 2018;1(3):e180756. PubMed
  2. Cioffi I, Evangelista A, Ponzo V, et al. Intermittent versus continuous energy restriction on weight loss and cardiometabolic outcomes: a systematic review and meta-analysis of randomized controlled trials. J Transl Med. 2018;16(1):371. PubMed
  3. Chowdhury A, Khan H, Lasker SS, Chowdhury TA. Fasting outcomes in people with diabetes and chronic kidney disease in East London during Ramadan 2018: The East London diabetes in Ramadan survey. Diabetes Res Clin Pract. 2019;152:166-170. PubMed
  4. Grajower MM, Horne BD. Clinical management of intermittent fasting in patients with diabetes mellitus. Nutrients. 2019;11(4):873. PubMed
  5. Ibrahim M, Davies MJ, Ahmad E, et al. Recommendations for management of diabetes during Ramadan: update 2020, applying the principles of the ADA/EASD consensus. BMJ Open Diabetes Res Care. 2020;8(1):e001248. PubMed

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

Fasting Also Interacts With Other Medications

Fasting has 2 major, 205 moderate known drug interactions in our database — the Insulin (Human) one above is among them. If you take anything else, check it against the full list below.

Major 2 Moderate 205 No known interaction 2,623 (incl. Insulin (Human))
Taking anything else?

Check Another of Your Medications Against Fasting

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

Everything else you take

See Every Supplement That Interacts With Insulin (Human)

This page covers Fasting only. If you take other supplements — a multivitamin, a sleep aid, something for joints — the Insulin (Human) page lists 259 supplements it has a documented interaction with, worst first, each one explained.

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

By severity: 3 major · 218 moderate · 38 minor.

From our pharmacist’s overview on the Insulin (Human) page

“With human insulin (Novolin, Afrezza), extra glucose lowering is not a nuisance, it is the hazard itself, and this is one of the lists I treat as genuinely serious. Nearly every ingredient here either drops blood sugar on its own or adds to insulin's effect, and the combination can push a normal dose into hypoglycemia, a dangerous low.”

Reviewed by 2 · Jul 18, 2026

Open the Insulin (Human) interaction page

How much people look this up

Where Fasting and Insulin (Human) 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 Fasting
Top half

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

29 days ago today
Medication Insulin (Human)
Top 10%

#213 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.

Eating pattern

About Fasting

What is Fasting?

  • Weight loss
  • Blood sugar control
  • Heart health
  • Religious or spiritual practice
  • General wellness and longevity

Fasting means voluntarily going without food (and sometimes drink) for set periods. Some research suggests it may help with weight loss and blood sugar in certain people, but results vary and quality of evidence is mixed. It is not safe for everyone, so check with your doctor or pharmacist before starting—especially if you take medication or have a health condition.

Read the full Fasting monograph & all interactions
Medication

About Human Insulin Injection

What Is Human Insulin Injection Used For?

Brand names: Novolin N, Novolin 70/30, Novolin R, Novolin L, Afrezza

Novolin (human insulin injection) is used to improve glycemic control — meaning blood sugar management — in adults and children with diabetes mellitus.

Novolin 70/30 is a fixed-ratio mixture of intermediate-acting and short-acting human insulin. Because the ratio is fixed, it cannot be adjusted separately for background (basal) or mealtime (prandial) needs.

See full Human Insulin Injection drug information
Keep checking

Other Drugs & Fasting

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

2Major
205Moderate
0Minor
2,622No known interaction
2 Major 205 Moderate 2,622 No interaction
Major

2 interactions

Moderate

205 interactions

Showing 60 of 205 moderate interactions — see all 205 on the Fasting page.

No interaction 2,622 drugs checked — show the list

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

Showing the 60 most looked-up of 2,622 medications checked with no known interaction — see the full Fasting list.

See the full Fasting interactions page
See every supplement checked against Insulin (Human), 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
Fasting monograph › Uses, safety, and every drug interaction in one place Insulin (Human) supplement interactions › Every supplement checked against Insulin (Human), ranked by severity Human Insulin 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

Following Fasting While Taking Insulin (Human): Common Questions

Can you follow Fasting while taking Insulin (Human)?
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.
Why are there 2 interactions listed for Fasting and Insulin (Human)?
Insulin (Human) belongs to more than one drug category, and Fasting interacts with each of those categories a little differently. We list every one so nothing is missed — your overall risk is driven by the most serious of them.
How serious is the Fasting and Insulin (Human) 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 (Human) and Fasting?

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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.