Diabetes and hyperglycemia

Diabetes is a metabolic disease that is characterized by “hyperglycemia” or elevated blood glucose levels. Diabetes is further classified into “Type I” and “Type II” diabetes – about $90\mathrm{\%}$‍ of diabetics are Type II and the remaining $10\mathrm{\%}$‍ are Type I. There are various differences between Type I and Type II diabetes regarding their causes and manifestations of diseases, but the primary difference is that Type I diabetics cannot produce insulin whereas Type II diabetics suffer from insulin resistance. In other words, Type II diabetics are able to secrete insulin, but the cells in their body are not able to respond appropriately to this insulin. In both cases, the end result is hyperglycemia – the body cannot uptake enough glucose into cells from the bloodstream.

Of note, untreated Type I diabetics are susceptible to “ketoacidosis”, which is characterized by an increase in blood ketone levels. The ketone levels can change the pH of the blood, specifically making it more acidic. Interestingly, Type II diabetics are not as susceptible to ketoacidosis. The synthesis of ketone bodies (hydroxybutyrate and acetoacetate) from acetyl CoA is shown in Figure 1. Notably, acetone forms from the spontaneous decarboxylation of acetoacetate. Although acetone does not serve as a ketone fuel (because it cannot be converted back to acetyl CoA), it contributes to the “sweet and fruity” odor that patients have when ketone levels are elevated.

Figure 1. Synthesis of ketone bodies hydroxybutyrate and acetoacetate from acetyl Co-A

Adapted from Wikipedia Commons - http://upload.wikimedia.org/wikipedia/commons/thumb/d/db/Ketone_bodies_synthesis.svg/585px-Ketone_bodies_synthesis.svg.png