What Is Lactic Acidosis In Type 2 Diabetes?

Lactic acidosis occurs when your body produces more lactic acid than it can handle. It can happen for a variety of reasons, the most common of which is strenuous exercise. Other factors include certain medications, chronic diseases, metabolic disorders, and lifestyle choices.

In some cases, lactic acidosis (LA) can be a medical emergency. Knowing how to prevent it is vital to your well-being. What is lactic acidosis in type 2 diabetes? Let's take a closer look.

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What is lactic acidosis?  

Lactic acidosis is a condition that occurs when the balance between production and use of lactic acid in the body is disturbed. If your body produces too much lactic acid, it may not be able to process it. When this happens, you may start suffering from lactic acidosis.

Lactic acid (also known as lactate) forms when your body starts breaking down carbohydrates to use for energy in situations when oxygen is low. It's a byproduct that develops when your body transfers energy from glucose to your cells without oxygen. 

The lack of oxygen often happens during intense exercises. It can also occur due to some health conditions that hinder the oxygen's transportation to body tissues.

In your body, lactic acid is formed in several different ways:

  • Muscle cells – lactic acid is a byproduct of a metabolic process (glycolysis) that the body uses to produce energy during intense exercise.

  • Red blood cells – red blood cells don't have mitochondria (part of the cell where respiration and energy production usually occur). That's why they have to get energy through anaerobic (without oxygen) glycolysis. Lactic acid is the end product of this metabolic process.

  • Gut bacteria – many species of bacteria take advantage of anaerobic respiration and produce lactic acid as a waste product. These species of bacteria live in your gut. The more sugar they eat, the more lactic acid they produce.

Generally, your body can deal with the excess lactic acid through metabolism. Blood carries lactic acid to the liver, where it's:

  • Broken down into carbon dioxide and water, or

  • Converted to glucose

However, your body's ability to remove lactic acid from your blood isn't limitless. When the lactic acid builds up, lactic acidosis occurs.

Types of lactic acidosis

There are three types of lactic acidosis:

Type A lactic acidosis

Type A lactic acidosis occurs when your tissues aren't receiving as much oxygen as they need for energy production. This initiates anaerobic glycolysis. 

Since lactic acid is a byproduct of anaerobic glycolysis, its amount increases. The overproduction of lactic acid in your tissues can lead to serious health consequences, including a lethal outcome.

The common examples of type A lactic acidosis are states of shock, ischemia (a condition when blood flow to organs is limited or restricted), seizures, and convulsions.

This type of acidosis is more serious than type B lactic acidosis.

Type B lactic acidosis 

Type B lactic acidosis is less common than type A lactic acidosis. It doesn't involve the restriction of blood flow to the tissue. It occurs when your cells can't process the amount of pyruvate (the end product of the metabolism of glucose).

When this happens, your body begins to look for alternative ways to deal with pyruvate through anaerobic glycolysis. This creates excess lactic acid and results in lactic acidosis.

There are three forms of type B lactic acidosis:

  • B1 – due to a chronic disease

  • B2 – caused by drugs and toxins

  • B3 – caused by rare genetic metabolic disorders (rare)

The common reasons behind this type of lactic acidosis are liver diseases, medications (epinephrine), trauma, excessive exercise, and diabetic ketoacidosis.  

D-lactic acidosis 

There is also a rare and highly specific form of lactic acidosis called D-lactic acidosis. It's limited to people who have short-bowel syndrome or have undergone a jejunoileal bypass operation (treatment for obesity). These patients usually experience lactic acidosis after consuming meals that are rich in carbohydrates.

Symptoms of lactic acidosis

Common symptoms of lactic acidosis include:

  • Stomach pain and discomfort

  • Diarrhea

  • Sweet-smelling breath

  • Headache

  • Fatigue

  • Weakness and sleepiness

  • Nausea

  • Vomiting

  • Confusion and disorientation

  • Jaundice (yellowing of skin and whites of the eyes)

  • Fast-beating heart

  • Muscle pains and cramps

The onset of this condition can be rapid but may also take several days. None of the symptoms are unique, and any of them could signal another health problem.

Since lactic acidosis can be a medical emergency, it's imperative to pay close attention to your condition. If symptoms persist, call 911. Continuous lactic acidosis could result in coma or death

Causes and risk factors

Common causes of lactic acidosis are diseases that involve low blood pressure and a lack of oxygen being delivered to your tissues. Such diseases include:

  • HIV 

  • Alcoholism 

  • Certain cancers 

  • Cirrhosis 

  • Kidney failure 

  • Respiratory failure 

  • Sepsis 

  • Short bowel syndrome 

  • Type 2 diabetes 

In rare cases, certain medications can cause lactic acidosis. They are:

  • Beta-adrenergic agonist inhalers - for asthma and chronic obstructive pulmonary disease

  • Epinephrine – for severe allergic reactions

  • Linezolid – for infections and pneumonia

  • Metformin - for treating diabetes (rare)

  • Propofol – for anesthesia and sedation

Another cause of lactic acidosis can be cyanide poisoning. Studies¹ show that cyanide's direct toxicity leads to lactic acidosis.   


Strenuous exercise is one of the most common reasons for mild type B lactic acidosis. When a person is putting excessive pressure on their muscles, they suffer from a lack of oxygen and initiate anaerobic glycolysis. This results in excessive lactic acid production.

Lactic acidosis after exercise typically isn't severe. A healthy body is usually capable of removing excess lactic acid. When exercise-related LA occurs, you could experience a burning sensation in your muscles as well as abdominal pain, weakness, and nausea. 


To diagnose lactic acidosis, your doctor measures the lactate levels in your blood by running a lactic acid test. Since blood in arteries has more oxygen than venous blood, your doctor may suggest taking blood from an artery. 

Your doctor will also conduct a physical exam and look for signs of:

  • Cardiogenic shock (happens when your heart can't pump sufficient blood for the body's needs)

  • Septic shock (severe drop in blood pressure)

  • Toxic shock (a serious condition caused by toxins)

  • Hypotension (low blood pressure)

  • Tachypnoea (rapid breathing)

  • Confusion

  • Low urine output

  • Abnormally high or low body temperature

  • Kussmaul's breathing (deep gasping breaths at normal or low frequency)

Your doctor may also run other tests to determine which underlying conditions may have caused the rise in lactate levels.


Lactic acidosis can cause severe complications that include:

  • Unconsciousness

  • Coma

  • Major organ failure

  • Cardiac arrhythmias

  • Shock

When lactic acidosis occurs, it's imperative to understand its cause and proceed with treatment. This can be complicated since the symptoms of lactic acidosis are often similar to the symptoms of other problems.

Therefore, prevention is key to dealing with this condition. People who are at higher risk of developing lactic acidosis need to know about the symptoms and consequences.

People who have type 2 diabetes, HIV, and/or chronic liver and kidney diseases have to work with their doctors to control their conditions and monitor medications that may cause lactic acidosis. It's also important to keep alcohol consumption under control.

Lactic acidosis and type 2 diabetes 

Type 2 diabetes is a major risk factor for developing lactic acidosis. A study² was done on people with and without diabetes who developed LA. The condition was more common in diabetics than in patients without diabetes. 

However, the study didn't demonstrate any significant increase in LA cases between patients who were on metformin and those that weren't. 

The contributing factors to lactic acidosis in people with type 2 diabetes were acute cardiorespiratory (heart and lung) disease, acute renal failure, and sepsis.  

The above study demonstrates that the use of metformin may not be a contributing factor for diabetics who develop lactic acidosis.

Metformin and lactic acidosis 

For some time, researchers have believed that metformin increased the chance of diabetics developing lactic acidosis. However, newer studies don't show major correlations between this medication and LA.

In 2010, a large systematic review³ was done to check whether LA is a risk factor for patients with type 2 diabetes. The review looked at the information from 347 metformin treatment studies and didn't find any evidence that metformin was associated with a higher risk of LA for diabetics.  

A 2018 study⁴ conducted by Danish researchers followed 10,652 patients with type 2 diabetes. Out of these people, 163 patients had symptoms of lactic acidosis. The study concluded that the use of metformin didn't increase the risk of developing lactic acidosis.

Metformin vs phenformin 

Metformin and phenformin are biguanides – a class of drugs that lower the level of glucose in patients with type 2 diabetes. These drugs were developed in the 1950s. While both were initially used for therapy, only metformin is currently available.

In the 1970s, studies demonstrated that people who used phenformin had a higher risk of developing lactic acidosis. Due to that, the medication was prohibited in the majority of countries.

Unlike phenformin, metformin doesn't increase blood lactate levels dramatically. People who take metformin are 20 times less likely to develop LA than those who take phenformin. However, this is only true when metformin is administered in therapeutic doses.

Metformin overdose 

Therapeutic doses of metformin cause a slight increase in lactate levels. Overdosing on metformin can lead to excessive lactate levels and lactic acidosis.

Since cases of metformin overdose are rare, more research needs to be done to evaluate the effects of excessive metformin consumption.

Lactic acidosis and diabetic ketoacidosis

Diabetic ketoacidosis (DKA) is a complication that can occur in people with both type 1 and type 2 diabetes. It happens when your body starts producing excessive amounts of ketones. The condition often develops when a person can't produce a sufficient amount of insulin.

When faced with a lack of insulin (a hormone that helps your body turn glucose into energy) or the inability to use it, the body starts looking for other ways to obtain energy. It may end up using the liver to break down stored fat. 

To do that, the body has to produce ketones. When too many ketones build up in the bloodstream, the person suffers from diabetic ketoacidosis.

The symptoms of ketoacidosis can develop as quickly as 24 hours. That's why people who live with type 2 diabetes have to monitor their condition closely. 

The key symptoms of diabetic ketoacidosis are similar to lactic acidosis. They include:

  • Excessive thirst

  • Frequent urination

  • Stomach pain

  • Nausea and vomiting

  • Weakness and fatigue

If you are experiencing any of these symptoms, you need to contact your doctor immediately.

People who suffer from diabetic ketoacidosis can also develop lactic acidosis. The lactate level is a marker of DKA's severity. A study⁵ that involved 62 DKA patients demonstrated that 55% of them had lactic acidosis, and 16% of them had severe LA.

A similar study⁶ involved 68 patients with diabetic ketoacidosis. It found that 68% of DKA patients had lactic acidosis, and 40% had severe LA. The study suggested the possibility that high lactate levels are associated with changes in glucose metabolism.

Both LA and DKA are the result of poor blood sugar management. If you have type 2 diabetes, you need to focus on consistent treatment. By keeping your glucose levels under control, you can avoid DKA and the associated LA.

Lactic acidosis in type 2 diabetes with other conditions

While studies show that taking therapeutic doses of metformin for type 2 diabetes doesn't usually cause lactic acidosis, LA can occur in patients with comorbidities. For example, if you have type 2 diabetes and kidney problems, the chances of developing lactic acidosis can be higher.

According to a 2015 Korean study,⁷ elderly patients with type 2 diabetes who have diseases and conditions that cause kidney problems need routine monitoring when receiving metformin treatment to screen for acidosis.

If you have diabetes and risk factors for lactic acidosis, you must be extra careful about monitoring your condition. You also need to discuss the possible side effects of the metformin treatment.

A large European review⁸ showed that metformin-associated lactic acidosis is a rare but fatal complication of metformin treatment. In the majority of cases, this problem was associated with underlying conditions and risk factors.

How to prevent lactic acidosis if you have type 2 diabetes 

If you have type 2 diabetes, you need to remember that lactic acidosis is a possible complication. While rare, LA can be dangerous and even fatal. When lactic acidosis begins, it can be hard to treat. That's why preventive measures are the key to avoiding consequences.

Speak to your doctor 

If you are diagnosed with type 2 diabetes, discuss the possibility of lactic acidosis with your doctor. Your physician is likely to explain what your chances of developing this problem are and how to minimize them.

It's important to share all your underlying conditions with your doctor. Since they may be risk factors for LA, your doctor needs to keep them in mind when prescribing medication, especially metformin.

Watch your blood sugar levels 

Even if you aren't taking any medication to control diabetes, you could still be at risk for developing LA. Uncontrolled glucose levels increase the risk of LA as well as the possibility of developing other health problems.

Make sure you are keeping your glucose levels under control by following the prescribed treatment closely. Hyperglycemia (high blood sugar) can cause diabetic ketoacidosis, which is frequently accompanied by LA.

Get treatment for underlying conditions 

If you have underlying conditions, such as kidney or liver problems, you need to make sure you are getting the right treatment. These conditions are risk factors for developing lactic acidosis regardless of the treatment you are getting for type 2 diabetes.

Since your liver is the key organ involved in removing lactic acid from your body, liver disease is a serious risk factor for LA.

Make lifestyle changes 

If you have diabetes, you need to pay close attention to your lifestyle to keep blood glucose levels under control and avoid developing lactic acidosis.

According to research,⁹ high doses of alcohol can cause type B lactic acidosis. That's why it's important to control your alcohol intake. 

Overall, if you follow your doctor's advice and do everything necessary to keep your blood sugar and medical problems in check, you are maintaining good strategies for LA prevention.

How to treat lactic acidosis when you have type 2 diabetes 

Treatment of lactic acidosis directly depends on the underlying conditions. By treating associated health issues, it's possible to reduce LA and its symptoms. 

However, if lactic acidosis is acute, it's a medical emergency. In this case, you could be admitted to the hospital where doctors may:

  • Put you on a cardiac monitor

  • Administer sodium bicarbonate and fluids intravenously

  • Administer oxygen to improve blood oxygenation and treat hypoxia (low oxygen in your tissues)

  • Arrange invasive ventilation to prevent hypercapnia (buildup of CO2 in your blood)

  • Administer insulin to treat hyperglycemia

  • Possibly arrange hemodialysis (clean your blood with a machine) for acute or chronic kidney dysfunction

During the treatment, your doctor will monitor blood lactate levels every two to six hours by taking blood tests.

Treatment for LA depends on many factors, including your initial condition and underlying health issues.

When to see a doctor 

The first symptoms of lactic acidosis are often similar to the symptoms of other conditions, including hyperglycemia. People who have type 2 diabetes have to pay close attention to the way they feel and contact their doctor when something seems different.

If you are experiencing severe symptoms, call 911. Severe lactic acidosis is a medical emergency. If not addressed immediately, it could lead to serious complications, including a fatal outcome.

The lowdown  

While rare, lactic acidosis in type 2 diabetes patients could cause serious complications. Diabetics with underlying conditions are more likely to develop LA. 

It's imperative to monitor your symptoms to get medical assistance for lactic acidosis as soon as possible. Severe LA is a medical emergency that usually requires hospitalization.

If you have type 2 diabetes, you can reduce the risks of lactic acidosis by managing blood glucose levels, treating underlying conditions, and leading a healthy lifestyle. Speak to your doctor about LA risk factors, treatment, and prevention.

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