A young woman with diabetic ketoacidosis

Learning issues in Type 1 Diabetes and Diabetic Ketoacidosis (DKA)

A 13 year old girl with diabetes was on treatment with Humulin (30/70) 48 units in the morning before breakfast and 24 units in the evening before dinner. She was admitted in Hospital in February 2009 for suspected diabetic ketoacidosis. On admission, she was lethargic and had a blood sugar of 12.1mmol/L. Her serum ketone tested positive.

Question: Where are the ketones being produced from?
Answer: The ketones are being produced in the liver from fatty acids.

Question: Why are the ketones being produced?
Answer: They are produced as fuel for the brain and heart when glucose is unavailable as fuel (because of insulin deficiency or because of starvation).

On Day 1, she was started on an insulin infusion of Actrapid 1unit per hour initially and after 3 hours this was increased to 2 units per hour. She was also given 2000ml of normal saline over 16 hour period.

Question: What is the initial dose of intravenous insulin in diabetic ketoacidosis?
Answer: 0.1units per kg body weight per hour (maximum of 10 units per hour)

Question: How much fluids should be given in diabetic ketoacidosis?
Answer: The amount of fluids needed and the speed at which it is given will vary according to the patient being treated. A general rule is that patients with diabetic ketoacidosis who are significantly dehydrated can be given 3 litres of fluid within 3.5 hours (1Litre in half an hour followed by 1Litre in one hour followed by 1Litre in 2 hours). This template must be modified in those with cardiac and renal dysfunction. After this initial fluid resuscitation period, the amount of fluids needed must be determined according the clinical condition of the patient (vital signs, degree of dehydration, urine output).

On Day 2, her blood glucose was 4.7mmol/L in the morning. Her serum ketones were still detectable and her anion gap was recorded to be 26mmol/L. The insulin infusion was continued at 2 units per hour and 1000ml of normal saline and 1000ml of dextrose 5 percent were given over 24 hours. Later that evening, her insulin infusion was increased to 4 units per hour because her blood glucose was 14.4mmol/L.

Question: What is the anion gap and when should it be determined?
Answer: The anion gap is a measure of anions in the blood other than chloride and bicarbonate. It is determined by the equation: (Na + K) – (Cl + HCO3) and is useful to distinguish between metabolic acidosis caused by accumulation of acids and metabolic acidosis caused by loss of bicarbonate.

Question: Why is 5 percent dextrose infused in her?
Answer: 5 percent dextrose (or 5 percent dextrose saline) is used in treatment of DKA because of the need to continue intravenous insulin infusion without developing hypoglycemia. A dextrose containing solution is started during insulin infusion when the plasma glucose is around 14mmol/L.

Question: Should potassium be given for all patients being treated for DKA?
Answer: Yes, it should be given unless there is hyperkalemia. The amount of potassium to be added in intravenous fluids will depend on the initial serum potassium level. If the initial serum K is normal, 1 to 1.5 grams of potassium chloride (contains 13 to 20mmol of K) can be added to each litre of fluid after the first half-hour. If the serum K is low, a higher amount of potassium should be given initially. Adjustments to the dose of potassium must be made according to serum potassium values(tested every 1 to 2 hours).

On Day 3, her blood glucose was 6.2mmol/L in the morning. Serum ketones were still detectable, but at a lower level. The insulin infusion was stopped and she was prescribed subcutaneous insulin: Actrapid 14units before breakfast, 14 units before lunch and 14units before dinner as well as Insulatard 12units at bedtime. IV fluids were stopped.

Question: When should insulin infusion be stopped in patients treated for DKA?
Answer: It should be stopped when the ketoacidotic state has been controlled. This can be recognised by clinical and biochemical parameters.

Question: How is the dose of subcutaneous insulin determined when intravenous insulin is stopped?
Answer: In patients with Type 1 diabetes, the total dose of subcutaneous insulin required per day should be calculated as 1 unit per kg body weight per day. Thus, for a patient weighing 50 kg, 25 units of insulin per day is the starting dose. Half of this (approximately 12 units) is given as short acting insulin and the remainder (13 units) as long acting insulin. The short acting insulin is given in three divided doses before meals while the long acting insulin is given before breakfast (two-thirds of the dose) and before dinner or bedtime (one-third of the dose).

On Day 4, her blood glucose was 8.3mmol/L in the morning. Her insulin regimen was changed to subcutaneous Humulin (30/70) 48 units in the morning before breakfast and 24units in the evening before dinner. On Day 5, the blood glucose was 5.2mmol/L in the morning. On Day 6, the blood glucose was 8.0mmol/L in the morning and 22.7mmol/L at 7.30pm. On Day 7, the dose of Humulin was increased to 52 units before breakfast and 28units before dinner.

Question: Why is the plasma glucose fluctuating so much after initiating insulin?
Answer: There are two reasons – 1. She may be eating more as she recovers and 2. The glucose surge after lunch is not being covered with insulin. As already mentioned, a patient with Type 1 diabetes needs short acting insulin before each meal.

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