There is a lot of confusion around ketosis and diabetic ketoacidosis. Some people think they are the same thing; others think ketosis leads to ketoacidosis. Neither of these notions are true.
To better understand the differences, let us understand precisely what the terms mean. As a disclaimer, the metabolic processes of the body are extremely complicated. There is much more to it all than just the liver and insulin but using these gives us a practical working model. As usual, if time is short you can go to tl;dr.
I have used a lot of internet searches and Wikipedia pages on the human metabolism to put this blog together. A couple of key sources of information were:
The Role of Insulin
To understand ketosis and ketoacidosis, we need to understand the role of insulin in the body. It is generally understood by many diabetics that insulin is needed to move glucose from the blood into cells. What is less well know is that insulin is also a control switch for the liver.
While the pancreas releases insulin based on the levels of glucose in the blood, the liver releases glucose into the blood based on the amount of insulin. Other hormones also influence this process but ignoring these external factors for simplicity, the liver and pancreas work together to keep the glucose in the blood stable, both producing small amounts of glucose and insulin respectively to keep the other in check. The doctors call such an equilibrium ‘homeostasis’.
If we consider the role of food, when carbohydrates are consumed, blood glucose goes up and insulin production is increased to move the glucose out of the blood. Similarly, the liver’s production of glucose goes down. When blood sugars return to a base level, the liver and pancreas also return to their homeostatic rate of production.
When someone chooses not to eat, the opposite occurs. With glucose in the blood not being replenished by food, glucose levels drop and the pancreas produces less insulin. This, in turn, encourages the liver to produce glucose to give the cells of the body the energy it needs.
In a world before widespread food transportation and refrigeration, winter meant a time of limited carbohydrates. Fortunately, the human body has some backup measures when times get tough.
The glucose stores of the liver are good for a day or two. As these run low, and insulin levels continue to drop, a new process ramps up. The protein sources of the body are broken down into amino acids and converted by the liver into glucose in a process called gluconeogenesis (other substances in the body are also used, such as lactate and glycerol but let us keep things simple).
This can keep the body going for a few days to a few weeks, depending on things like diet (protein sources can be found in the winter, after all). After this, and the insulin levels drop a little further, the fat stores of the body are broken down into fatty acids. Different parts of the body can use fatty acids and amino acids as alternative fuel sources to glucose so, even with a low carbohydrate diet, the body can maintain the necessary energy levels.
If carbohydrate fasting continues, insulin levels keep dropping and there are sufficient fatty acid levels in the blood, another process kicks in to convert fatty acids into ketones, yet another fuel source which can be used by the brain and muscles (a commonly held misconception is that the brain can only use glucose as a fuel source; it is simply not true). This final process of converting fatty acids into ketones is called ketosis.
In a body with a low but sufficient level of insulin, ketosis is regulated and poses no threat. In the muggle (non-diabetic person) body, it is very difficult to go below the threshold where ketosis becomes a problem. To do so requires literal starvation or large amounts of alcohol over an extended period of time. Starvation can be understood as an extension of the explanation above. Alcohol causes a problem by blocking the liver’s ability to generate glucose from the energy stores and amino acids, forcing the overproduction of ketones.
For the diabetic, where insulin production is impaired, it is much easier to go below the threshold. This is why insulin-dependent diabetics, whose pancreas cannot maintain a basal level of insulin, do so through a pump or via the injection of long-acting insulin. For non-insulin-dependent diabetics, one path to ketoacidosis is feeding the body fast-acting carbohydrates which flood the blood with glucose and overwhelm the pancreas. The insulin in the blood becomes depleted and the liver goes unchecked.
With no insulin to regulate it, the liver goes into energy production overdrive, running all of the energy production processes as quickly as possible. The body is flooded with glucose and ketones and, while the excess can be removed from the body through urination, even this has its limits. The ketones begin to accumulate, changing the pH (acidity) of the blood. This has knock-on effects throughout the body leading to sickness and often vomiting. If not dealt with, ketoacidosis can lead to coma and death.
The Key Differences
While ketosis is a state of low dietary carbohydrate, ketoacidosis is a state of low insulin in the blood, which is almost impossible to generate through a lack of eating, except in extreme cases of starvation. A diabetic who maintains a basal level of insulin in their blood will not go into diabetic ketoacidosis (DKA) from a low carbohydrate diet. It is simply not possible.
The manifestation of the two in the body is also different. While someone in ketosis will have a low/normal blood glucose and generally feel fine, someone in ketoacidosis will have elevated blood sugar levels, be urinating frequently e.g. a full bladder every 30 minutes, may feel thirsty and be dehydrated, and feel ill. Unfortunately, there is no over-the-counter test for serum insulin levels (the amount of insulin in the blood) or blood acidity levels, which would provide a definitive answer to a concerned diabetic.
A rare form of DKA is Euglycemic DKA (EDKA). In this case, the body is flooded with ketones but blood glucose levels are normal. This usually occurs when there is extremely low insulin levels in the blood and the liver also has low glucose stores. This is something to watch out for if, for example, you are fasting. It is also the reason why it is vital to ensure you always have a sufficient basal level of insulin.
As EDKA does not present with high blood sugars, it is often missed by doctors. If you suspect you could have EDKA tell your health care team of your suspicion and insist they measure your blood pH which is the definitive test for DKA and EDKA (reference: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5592704/).
In terms of treatment, DKA and EDKA are treated the same way: hydration and insulin to bring ketosis back under control.
Ketosis and diabetic ketoacidosis (DKA) are not the same thing. While ketosis is triggered through an extended lack of dietary carbohydrate, DKA is triggered by the exhaustion of insulin in the blood; the consequence of which is the liver over-producing fuel for the body, including ketones which, when they accumulate, can turn the blood acidic and lead to death.
Treatment for DKA is re-hydration and the re-introduction of insulin back into the blood.