Supplements and Sitagliptin.
Sitagliptin, sold under the brand name Januvia, is a dipeptidyl peptidase-4 (DPP-4) inhibitor: it prolongs the action of incretin hormones.
Sitagliptin is a DPP-4 inhibitor (dipeptidyl peptidase-4). Use is Type 2 diabetes as a second or third line oral agent. The class prolongs the action of endogenous incretin hormones (GLP-1 and GIP) by blocking their degradation, which raises insulin release in a way tied to glucose with low hypoglycaemia risk. UK prescribing centres on sitagliptin, linagliptin, alogliptin, and saxagliptin. The supplement surface is small because DPP-4 inhibitors have minimal CYP metabolism. Linagliptin is the cleanest in this respect. Clinical issues here are mostly glycaemic and additive. Berberine, cinnamon at extract doses, alpha lipoic acid, and chromium at high doses all carry small additive HbA1c effects. The stack rarely causes hypoglycaemia, but it is worth tracking in patients on tight glycaemic targets. Acute pancreatitis is a rare adverse effect flagged for the class.
Below are the 7 documented pairs we have explicitly assessed against Sitagliptin in the Distil database: 7 amber. The pairs cluster around 2 mechanisms: Reduced glucose control and Additive glucose lowering. Every call is cited to either a clinical reference (PMID) or the British National Formulary. Anything not on this list is either still to be assessed or beyond our database scope. The checker beneath surfaces assessments by supplement, and the missing-item form at the bottom of the page routes any uncatalogued supplement into our next curation pass.
Documented interactions
Last reviewed 14 June 2026. Each interaction below lists the evidence its assessment drew on: some rest on studies of the exact pair, others on mechanism evidence, where a citation may support one part of the reasoning rather than the exact combination. The evidence line on each entry says which.
Reduced glucose control
Amber Does Melatonin interact with ?
Melatonin can blunt the body's insulin response and raise blood sugar after eating, which works against the blood-sugar control that sitagliptin is helping with. The effect is strongest when melatonin and food are taken close together, so if you take sitagliptin it is best to keep melatonin well away from your evening meal and to mention it to your prescriber if your blood sugar is being monitored.
Evidence: Based on an established mechanism, with no direct study of this exact combination yet.
Reviewer-flagged: awaiting clinical-reviewer sign-off.
Additive glucose lowering
Amber Does Alpha Lipoic Acid interact with ?
Alpha lipoic acid may lower blood sugar by improving how your body responds to insulin. Sitagliptin also lowers blood sugar, so the two may add up. The combination is usually manageable because sitagliptin rarely causes low blood sugar on its own, but monitor your glucose when you start alpha lipoic acid or change the dose.
Evidence: Supported by human study data.
Reviewer-flagged: awaiting clinical-reviewer sign-off.
Amber Does Berberine interact with ?
Berberine lowers blood sugar, and sitagliptin does too. It is worth monitoring your glucose when you start berberine and letting your GP know; the combination is usually well tolerated because sitagliptin rarely causes low blood sugar on its own.
Evidence: Based on an established mechanism, with no direct study of this exact combination yet.
Reviewer-flagged: awaiting clinical-reviewer sign-off.
Amber Does Garlic Extract interact with ?
Garlic supplements may lower blood sugar a little on their own. Sitagliptin also lowers blood sugar but rarely pushes it too low on its own, so the combination is generally manageable. Still, monitor your glucose when you start a garlic supplement or change the dose.
Evidence: Limited human data, based on case reports and a known mechanism.
Reviewer-flagged: awaiting clinical-reviewer sign-off.
Amber Does Holy Basil interact with ?
Holy basil (tulsi) may lower blood sugar on its own. Sitagliptin also lowers blood sugar, so the two may add up. The combination is usually manageable because sitagliptin rarely causes low blood sugar on its own, but monitor your glucose when you start holy basil or change the dose.
Evidence: Limited human data, based on case reports and a known mechanism.
Reviewer-flagged: awaiting clinical-reviewer sign-off.
Amber Does Pine Bark Extract interact with ?
Pine bark extract (pycnogenol) may lower blood sugar a little on its own. Sitagliptin also lowers blood sugar but rarely pushes it too low on its own, so the combination is generally manageable. Still, monitor your glucose when you start pine bark extract or change the dose.
Evidence: Limited human data, based on case reports and a known mechanism.
Reviewer-flagged: awaiting clinical-reviewer sign-off.
Amber Does Psyllium Husk interact with ?
Psyllium lowers blood sugar a little on its own, which can add to sitagliptin's effect. Sitagliptin on its own rarely causes low blood sugar, so the practical risk is small, but keep an eye on your glucose when you first start regular psyllium, especially if sitagliptin is combined with a sulfonylurea or insulin.
Evidence: Limited human data, based on case reports and a known mechanism.
Reviewer-flagged: awaiting clinical-reviewer sign-off.
What this list does not say. Pairs not flagged here are not implicitly safe. They are either not yet in our database, or fall outside our inclusion scope (food-supplement interactions only; for drug-drug interactions, the BNF is authoritative). Use the checker below to surface any supplement, and submit a missing item if you take something we have not catalogued.
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How we grade severity, choose what's in scope, and what we exclude.
Every call on this page is reasoned. We publish the full rubric for severity tiers, the medication inclusion logic, the evidence grades we accept, and what we deliberately leave out. About three thousand words. Worth reading once if you use this tool more than occasionally.
Read the full methodologyA full supplement review, built around you, not a generic stack.
The free checker answers one interaction question at a time. A Distil report reviews the bigger picture: your goals, diet, medications, current supplements and any blood results you provide, then shows what appears worth keeping, changing, adding or leaving out.
- what your diet already covers, so you are not adding a capsule for something food is already handling
- which evidence-graded compounds are worth considering for your goals, and which were considered but left out
- what to keep, change or stop from what you already take, plus the order to introduce anything new
- how your medications and complete supplement stack fit together, with daily timing and a clear point for reassessment
The interaction check is one section of the full report. You also get the reasoning behind each recommendation and the evidence references used.
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