The four named ingredients
Berberine, gymnema sylvestre, cinnamon bark and chromium, described as they are generally understood.
Four ingredients are named for GlucoPril on the seller's official pages. Each is described here as it is generally understood — what the plant or mineral is and where it comes from.
No quantity appears below, because none is published. Nothing here is a claim about what the finished formula does, which has not been studied.
A caveat first
The seller's pages do not all list the same ingredients. One names these four, another names eight, and a marketplace listing names a formula that looks like a different product entirely. These four are the ones the official pages agree on. A Supplement Facts panel on the delivered bottle outranks all of them, including this page.
Berberine
A bitter yellow alkaloid, extracted from the roots, stems and bark of several unrelated plants — barberry, goldenseal, Oregon grape and tree turmeric among them. The colour is distinctive enough that it was used as a dye long before anyone studied it.
Of the four names on this label it carries by far the largest body of modern research, and also the clearest caution: berberine is known to interfere with the way a number of prescription medicines are metabolised. Anyone already taking something should raise it with a pharmacist rather than with a website.
Gymnema Sylvestre
A woody climbing vine native to the forests of India, Africa and Australia. Its Hindi name is gurmar, which translates as sugar destroyer, and it earns the name in a way anyone can test: chewing the leaf temporarily removes the tongue's ability to taste sweetness.
That effect on taste is real, immediate and well documented. What happens after the leaf is swallowed is a separate question, and the two are worth keeping apart, because the striking one is the one usually quoted.
Cinnamon Bark
The inner bark of trees in the Cinnamomum genus, peeled, dried and curled into the quills sold as a spice. Two kinds are in common use: Ceylon, sometimes called true cinnamon, and the cheaper cassia. They differ in their coumarin content, which is why the distinction matters in a supplement and not much in a bun.
Which of the two is used here is not published, and neither is the amount. Both would be worth knowing.
Chromium
The only mineral among four botanicals. Chromium is an essential trace element: the body needs a small quantity, cannot manufacture it, and gets it from ordinary food — broccoli, whole grains, meat, brewer's yeast.
Its formally recognised role is in normal macronutrient metabolism, which is regulator-approved phrasing for a function rather than an outcome. It is the one entry on this label with an established nutritional job, which is a more modest claim than an effect.
The limit of this page
No trial has been published on GlucoPril itself. Research describes an ingredient at a stated dose, in a stated population; with no dose disclosed here there is nothing to line it up against, and nothing above should be read as a claim that this product treats or prevents anything.