Hyperglycemia (elevated blood glucose levels), ketoacidosis, and coma

The goal of diabetes treatment is freedom from symptoms and the prevention of long-term complications. To achieve this, elevated blood glucose levels are lowered through diet and physical activity, oral medications, and insulin.

As a rule, diabetes therapy aims for near-normal blood glucose values between 90 and 180 mg/dl (5–10 mmol/l). Higher blood glucose levels (hyperglycemia) lead to mild to severe symptoms and, in the long term, to complications.

Acute symptoms caused by high blood glucose levels

Mild elevations in blood glucose often go unnoticed. Early signs of elevated values, such as fatigue and weakness, are frequently underestimated, especially in older people. This is why the diagnosis of “diabetes” is often made very late, sometimes only for the first time during a severe metabolic decompensation with coma.

Early signs of elevated blood glucose are:

  • Weakness
  • Fatigue
  • Low mood / depression
  • Increased thirst and dry mouth
  • Increased urination
  • Visual disturbances
  • Itching of the skin

Signs of rising and very high blood glucose levels include:

  • Weight loss
  • Muscle pain and cramps
  • Abdominal pain
  • Nausea and vomiting
  • Confusion and impaired consciousness
  • Deep breathing with an acetone odor
  • Loss of consciousness

Causes of elevated blood glucose levels (hyperglycemia)

Common causes of elevated blood glucose levels in people with diabetes include increased insulin requirements (typically during infection, fever, or inflammation, and when taking certain medications) and insufficient insulin supply (forgotten injections, pen defects, expired insulin, or omission of insulin when not eating, catheter problems in insulin pump patients).

However, insulin requirements may also increase gradually without any obvious “error,” due to declining endogenous insulin secretion and the development of insulin resistance (e.g., with weight gain), making dose adjustments necessary.

Checklist for high blood glucose levels

  • Fever, infection, pain?
  • New medications (e.g., corticosteroids)?
  • Insulin injected reliably?
  • Leakage from the insulin pen cartridge?
  • Needle blocked? Inject 2–4 units under visual control onto a tissue or into a cup.
  • Expiration date of the insulin vial?
  • Errors in blood glucose measurement (test strips expired? incorrect coding)?
  • Injection site problems (hardening, lipohypertrophy)?

Next stages: acetone and diabetic coma

With rising blood glucose levels (above 240 mg/dl or 13.3 mmol/l), a dangerous situation with a complicated course can develop, which must be prevented in all cases. Every person with diabetes must be informed about the development of this complication, early recognition, and appropriate countermeasures (education/training).

As blood glucose levels rise, the following processes play a dangerous role:

  • The body attempts to eliminate the large amounts of glucose through increased urination. This leads to severe fluid loss with dangerous electrolyte imbalances and circulatory disturbances, potentially progressing to shock.
  • To generate energy, fat is broken down. This produces so-called ketone bodies (acetone), leading to acidification of the blood. These ketone bodies cause nausea and vomiting (further fluid loss, no food intake, and often mistakenly no insulin administration), as well as reduced sensitivity to insulin (insulin resistance). Therefore, higher insulin doses are required to lower elevated blood glucose levels than would otherwise be necessary.
  • Subsequently, clouding of consciousness and unconsciousness occur – the so-called acetone coma, a life-threatening condition.

Keyword: “Ketone bodies”

During energy production from fat breakdown, small amounts of acetoacetate are produced daily in the body but are immediately broken down. Only with excessive fat breakdown does acetoacetate rise sharply in the blood (ketonemia) and become measurable in the urine. Insulin requirements are then significantly increased.

Ketone bodies also occur in healthy individuals after prolonged fasting and after intense physical exertion.

Ketoacidotic coma is always the result of an absolute insulin deficiency. Therefore, it usually occurs only in type 1 diabetes. In type 2 diabetes, insulin is typically still present, so fat breakdown with acetone formation does not occur. As a result, very high blood glucose levels (over 600 mg/dl or 33 mmol/l) can develop before loss of consciousness occurs. This is known as hyperosmolar coma (more on this below).

Recognizing and treating ketoacidosis

The described symptoms of elevated blood glucose levels are nonspecific; therefore, blood glucose measurement must always be performed. Initial treatment depends on the established treatment regimen, for example, an additional dose of insulin for correction according to a physician-defined table (correction factor).

Warning: If ketone bodies (acetone) are produced, there is particular danger, and different rules apply for correction. Ketone bodies can be detected in the urine.

At values above 240 mg/dl (13.3 mmol/l), urine should be tested for ketone bodies / acetone. The detection of ketone bodies / acetone is a serious sign of illness. This can be done using ketone test strips (available at pharmacies) via urine testing or using a device that measures ketone bodies in the blood.

Emergency rules when ketone bodies are detectable

  • If possible, do not be alone
  • Minimize physical activity
  • Drink plenty of water (1 liter within 1 hour)
  • Inject insulin even if you cannot eat or are vomiting: 20% of the total daily insulin dose (rapid-acting and long-acting insulin – see example)
  • Measure blood glucose and acetone every 2 hours
  1. Values over 240 mg/dl (13.3 mmol/l), acetone positive: repeat 20% of the total insulin requirement
  2. Values 180–240 mg/dl (10–13.3 mmol/l), acetone positive: 10% of the total insulin requirement
  3. Values under 180 mg/dl (10 mmol/l), no acetone: no additional insulin, continue drinking, eat 2 additional bread units (BE)
  • If blood glucose continues to rise or control is lost, contact a doctor or hospital

After normalization of blood glucose and negative acetone: analyze the cause.

Example

You normally inject 10 IU of long-acting insulin (NPH) in the morning and at night. For main meals, you inject on average 10 IU in the morning, 15 IU at midday, and 15 IU in the evening of regular (short-acting) insulin.

This results in a total of 60 IU of insulin per day.

Now, due to an infection, blood glucose has risen to 280 mg/dl, and acetone in the urine test is strongly positive (3+).

Procedure: Inject 20%, i.e., 12 IU of regular insulin, and re-measure blood glucose and urine acetone after 2 hours.

In type 2 diabetes: hyperosmolar coma

Hyperosmolar coma usually develops slowly and can be effectively treated with additional insulin at any stage before impaired consciousness occurs. It most commonly occurs in older patients with type 2 diabetes. Extremely high blood glucose levels may occur (over 800 mg/dl or 45 mmol/l). These metabolic decompensations always require hospital admission.

The most important preventive measure is adequate fluid intake. If consciousness begins to be impaired, hospital treatment is absolutely necessary and must be initiated promptly.