They are metabolic drugs with a neuropsychiatric signal
Nutritious, fiber-rich fruits and vegetables can also help stabilize blood sugar by slowing digestion and the absorption of sugar into the bloodstream
The question is what you get for your money, and that is where the reviews tell the real story

Water, Dipropylene Glycol, Glycerin, Niacinamide, Octyldodecanol, Helianthus Annuus (Sunflower) Seed Oil, Butylene Glycol, Trehalose, Pentylene Glycol, 1,2-Hexanediol, Eriobotrya Japonica Leaf Extract, Coptis Japonica Root Extract, Mentha Viridis (Spearmint) Extract, Sodium Hyaluronate, Theobroma Cacao (Cocoa) Extract, Centella Asiatica Leaf Extract, Argania Spinosa Kernel Oil, Sesamum Indicum (Sesame) Seed Oil, Chitosan, Serenoa Serrulata Fruit Extract, Caprylyl Methicone, Panthenol, Polymethylsilsesquioxane, Propanediol, Hydroxyethyl Acrylate/Sodium Acryloyldimethyl Taurate Copolymer, Cetearyl Olivate, Polyglyceryl-10 Behenate/Eicosadioate, Ammonium Acryloyldimethyltaurate/VP Copolymer, Sorbitan Olivate, Acrylates/C10-30 Alkyl Acrylate Crosspolymer, Tromethamine, Ethylhexylglycerin, Sorbitan Isostearate, Adenosine, Palmitic Acid, Hydrogenated Lecithin, Glutathione, Phosphatidylcholine, Polyglyceryl-10 Laurate, Dilauryl Thiodipropionate, Pentaerythrityl Tetra-di-t-butyl Hydroxyhydrocinnamate, Sodium Phytate, Allantoin, Madecassoside, Lecithin, Cellulose, Sodium Phosphate, Polyglutamic Acid, Dextrin, Asiaticoside, Cysteine, Tocopherol, 3-0-Ethyl Ascorbic Acid, Arbutin, Bisabolol, sh-Oligopeptide-1, sh-Oligopeptide-2, sh-Polypeptide-1, sh Polypeptide-10, sh-Polypeptide-11, sh-Polypeptide-3, sh-Polypeptide-59, sh-Polypeptide-9, Cholesterol, Ascorbic Acid, Beta-Sitosterol, Ascorbyl Glucoside, Ceramide NP, Xanthan Gum, C12-16 Alcohols

It may also be related to eating significantly less, dehydration, changes in blood sugar, nausea, or the body adjusting to a new routine