The smell of Diabetes

Blog

Jan 30

The Smell of Diabetes

Diabetes in a Nutshell

Diabetes (from the Greek διαβήτης, diabètes, derivative of διαβαίνω, diabàino, « passing through») is a term that identifies pathologies characterized by polyuria (overproduction of urine), polydipsia (excessive thirst and consequent abundant water consumption), and polyphagia (abnormally strong sensation of hunger). Usually, the aforementioned term refers to a chronic disease belonging to a group of pathologies that affects how the body uses sugar, called diabetes mellitus. Diabetes is then characterized by high levels of glucose in the blood, caused by a total or partial deficiency of the hormone responsible for the regulation of sugar in our system: insulin. [^1]

A Closer look

Glucose is the primary metabolic fuel for the brain. An individual with a shortage of glucose could then incur in severe consequences.

Animals, during their evolutive process, were able to develop complex hormonal mechanisms in order to grant a steady glucose concentration in the blood, thus satisfying the brain’s energetic requirements while avoiding to run into severe physical repercussions derived from higher levels of sugar in the blood.

However, subjects affected by the insulin-dependent diabetes mellitus are not able to produce a sufficient quantity of the insulin hormone that would be used to lower the levels of glucose in the blood.

How do cells absorb the glucose in the blood stream?

Insulin regulates metabolic enzymes and gene expression. Moreover, insulin doesn’t penetrate the cell, but interacts directly with the INSR receptor, which, after being activated by its ligand, carries out of autophosphorylation. This process involves a part of the receptor containing kinase activity located in the cytoplasm.

This process opens the active site and domain with kinase activity, triggering the phosphorylation cascade. This results in the activation of two proteins, MEK and ERK, which enter the cell nucleus and phosphorylate growth factors such as ELK1. This modulates the transcription of 100 genes regulated by insulin, causing insulin to act as a growth factor.

The transcription of some of these genes causes the synthesis of the glucose transporters (GLUT), which position themselves on the cell membrane, thereby sequestering the glucose from the blood. Patients that suffer from diabetes who lack said transporters, are unable to absorb glucose and, therefore, both the skeletal muscle and the brain use fatty acids as metabolic fuel.

In the liver, fatty acids are converted into acetyl-CoA, which will later be converted into ketone bodies (acetone, acetoacetate and beta-hydroxybutyrate) which will then be transferred to other tissues in order to be used as energy sources. In this circumstance, the brain uses ketone bodies as an alternative to glucose.

In type 1 diabetes, excess ketone bodies in the blood lower its pH, leading to potentially fatal condition of ketoacidosis. Acetone, which is highly volatile, is expelled through respiration.

The smell of diabetes

These ketonic bodies are what makes us potentially aware of diabetes. Acetone has a strong solvent smell, similar to that of nail polish remover, while acetoacetate has a fruity smell, and butyrate has the smell of ripe fruit.

Both the skin and breath of an individual could carry distinguishable traits of these smells. Would it then be possible to refine this diagnostic technique, thus preventing the deterioration of said condition?

A similar topic has been tackled in this article, where the olfactory potential of each functional group has been analysed.

Sources and information