Beta cells secrete insulin in response to increases in blood glucose. Insulin signalling controls access to blood glucose in body cells. Insulin is produced in response to rises in blood glucose levels. Hydrolysis of sucrose yields glucose and fructose. The metabolism of glucose and insulin are also influenced. Its effect is opposite to that of insulin, which lowers extracellular glucose. Incretins are a group of metabolic hormones that stimulate a decrease in blood glucose levels. Hydrolysis breaks the glycosidic bond converting sucrose into glucose and fructose. Average blood glucose concentrations can also be measured. "Mixtos" use both glucose and fructose sugars. Maltase breaks maltose into two units of either glucose or fructose. Sucrose is a disaccharide made up of glucose and fructose. Thiamine is required for metabolism including that of glucose, amino acids, and lipids. Xanthan gum is produced by the fermentation of glucose and sucrose. MafA is degraded by proteasomes upon low blood glucose levels.