The terms ketosis and ketoacidosis sound similar and both involve ketones, but they refer to very different metabolic states.
Ketosis is a normal and regulated process, whereas ketoacidosis is a serious medical condition. And Understanding the difference is important.
What Is Nutritional Ketosis?
Ketosis is a natural metabolic state that occurs when carbohydrate intake is low and the body shifts toward using fat as its primary fuel source.
As fat is broken down, the liver produces ketones, which can be used for energy by the brain and other tissues. The major ketone found in the body is beta-hydroxybutyrate (BHB), which can be measured in the blood.
Nutritional ketosis is typically defined by BHB levels between 0.5 to 3.0 mmol/L, and euketonemia extends that range up to 5.0 mmol/L for therapeutic applications. However, in some cases – such as individuals who undergo extended fasting or use ketogenic diets therapeutically – ketone levels may rise above 5.0 mmol/L without causing any harm.
This is because euketonemia is regulated by insulin and other hormones, which help maintain balance and prevent ketone levels from becoming excessive.
What Is Ketoacidosis?
Ketoacidosis – most commonly in the form of diabetic ketoacidosis (DKA) – is a serious, potentially life-threatening condition.
Importantly, DKA is not defined by high ketone levels alone. It is characterized by the following triad:
- Elevated blood glucose levels, typically >240 mg/dL(13.3 mmol/L), although sometimes lower
- Elevated beta-hydroxybutyrate (BHB) levels, typically >10 mmol/L, although sometimes lower
- Metabolic acidosis, defined as a blood pH below 7.3 and/or bicarbonate levels below 18 mEq/L
This combination reflects a breakdown in normal metabolic regulation due to insufficient insulin. DKA occurs primarily in people with type 1 diabetes and, much less commonly, in people with type 2 diabetes under certain conditions.
Importantly, although in diabetic ketoacidosis BHB levels are typically above 10 mmol/L, it can be detected at levels of 3.0 mmol/L or higher. More concerning than a specific number is a rapid rise in ketones – especially when accompanied by symptoms – which warrants close monitoring.
Why Ketoacidosis Occurs
Under normal circumstances, insulin helps regulate both blood glucose and ketone production.
When insulin levels are inadequate – such as with missed insulin doses or during illness – the body:
- Releases large amounts of glucose into the bloodstream
- Produces ketones at an uncontrolled rate
- Becomes increasingly acidic
This can disrupt normal organ function and requires urgent medical treatment.
Can a Ketogenic Diet Cause Ketoacidosis?
For individuals without diabetes or with normal insulin signaling, developing ketoacidosis through diet alone is extremely unlikely.
Even when carbohydrate intake is very low, the body continues to produce enough insulin to:
- Prevent excessive ketone production
- Maintain normal blood pH
- Keep blood glucose within a safe range
As a result, nutritional ketosis remains a regulated and stable metabolic state, not a dangerous one.
Important Considerations for Diabetes and Certain Medications
People with type 1 diabetes are at risk for DKA if they do not have adequate insulin in their system, regardless of their dietary approach. Those who follow a ketogenic lifestyle should monitor their ketone levels regularly in order to establish a baseline, understand their usual fluctuations, and make adjustments as needed.
Individuals with type 2 diabetes who take SGLT2 inhibitors, such as Jardiance or Farmiga, have an increased risk of a form of ketoacidosis known as euglycemic DKA, which can occur even when blood glucose levels are not significantly elevated.
In this setting, ketoacidosis may develop at lower blood glucose and ketone levels than typically seen in DKA, making it more difficult to recognize based on glucose alone.
For this reason, individuals taking SGLT2 inhibitors should:
- Monitor blood glucose and ketone levels regularly
- Be aware that ketone elevations may require prompt attention
- Work closely with their healthcare provider, who can establish an appropriate BHB range and advise when it may be necessary to hold or discontinue the medication
Signs and Symptoms of Ketoacidosis
Common warning signs of DKA include:
- Elevated blood glucose (often above 240 mg/dL, although normal or only slightly elevated in euglycemic DKA)
- Elevated blood ketones combined with other symptoms listed
- Excessive thirst and frequent urination
- Nausea or vomiting
- Abdominal pain
- Fatigue or confusion
- Rapid or labored breathing
- A strong acetone (fruity) odor on the breath
If these symptoms occur, immediate medical attention is required.
Importantly, although in diabetic ketoacidosis BHB levels are typically above 10 mmol/L, it can be detected at levels of 3.0 mmol/L or higher. More concerning than a specific number is a rapid rise in ketones – especially when accompanied by symptoms – which warrants close monitoring.
Take Home Points
Diabetic ketoacidosis (DKA) is not defined by ketone levels alone. It is a medical emergency characterized by the combination of high blood glucose, elevated ketones, and metabolic acidosis.
By contrast, nutritional ketosis is a normal, regulated metabolic state. BHB levels can vary, and in some cases they may rise above 5 mmol/L without jeopardizing safety.
For individuals with normal insulin function, the body maintains tight control over ketone production and acid-base balance. This is why ketoacidosis cannot develop from diet alone in people without diabetes or proper insulin signaling, even when ketone levels are elevated.
However, people with type 1 diabetes, as well as those taking SGLT2 inhibitors, have an increased risk of ketoacidosis and should monitor glucose and ketones closely and follow medical guidance.
