Amelia Bruce is 5 years old, she presents to the Emergency Department with her mother. Amelia has been unwell for several days with a fever and vomiting. This morning her mother became very worried because Amelia has been very sleepy and was difficult to wake. She has been passing lots of urine and drinking "a lot more than usual".
On Initial assessment: Alert, Pink, well perfused, looks unwell.
Temp: 38°C | RR: 30/min | HR: 130 bpm | BP: 80/50 | SaO2: 95% [RA]
The diagnosis of DKA is usually straightforward as long as the symptoms are not misdiagnosed for more common conditions such as:
Key components of the medical history:
Key components of the clinical examination:
Investigation will both aid in diagnosis and determine the severity of DKA.
| Severity | Blood glucose mmol/L | Venous pH | Bicarbonate mmol/L |
|---|---|---|---|
| Mild | >11 | <7.3 | <15 |
| Moderate | >11 | <7.2 | <10 |
| Severe | >11 | <7.1 | <5 |
The diagnosis of DKA is demonstrated by hyperglycaemia with ketonaemia or heavy ketonuria, and acidosis.
Hyperglycaemia is demonstrated by dipstick, while a blood sample is sent to the laboratory for confirmation. A venous blood sample is taken for blood gas analysis. From this a rapid ketone level can be measured in the plasma.
| Blood ketones (mmol/L) | Urine Ketones | Interpretation |
|---|---|---|
| <0.6 | Negative | If BGL <5.5 - suggests starvation state. Start fluids |
| 0.6 - 0.9 | Trace | If BGL <5.5 - suggests starvation state. Start fluids |
| 1.0 - 2.0 | Moderate | If BGL >10 - increased risk of DKA. Start fluids + insulin |
| >2.0 | Large | Emergency - initiate DKA protocol immediately |
The principles of management are as follows:
1. Replace the fluid losses with physiological saline (0.9%), slowly to avoid cerebral oedema.
2. Replace the electrolyte losses. Potassium levels need to be monitored with great care. Patients have a total body potassium deficit although initial plasma levels may not be low. Insulin therapy leads to uptake of potassium by the cells with a consequent fall in plasma K+ levels. Potassium is therefore given as soon as insulin is started, unless the patient is anuric or known to have renal failure, in which case wait for serum electrolytes.
3. Restore the acid-base balance. A patient with healthy kidneys will rapidly compensate for the metabolic acidosis once the circulating volume is restored. Bicarbonate is seldom necessary and is sometimes associated with paradoxical worsening of cerebral acidosis and hypokalemia. It is only considered in patients with cardiogenic shock, symptomatic hypokalemia or if the pH is below 7.0, and is best given as an isotonic solution.
4. Replace the deficient insulin. Modern treatment is with relatively modest doses of insulin, which lower blood glucose by suppressing hepatic glucose output rather than by stimulating peripheral uptake, and are therefore much less likely to produce hypoglycaemia. Soluble insulin is given as an intravenous infusion where facilities for adequate supervision exist (0.05-0.1 u/kg/hr IV).
5. Monitor fingerprick blood glucose closely. Hourly measurement is needed in the initial phases of treatment.
6. Replace the energy losses. When plasma glucose falls to near-normal values (15 mmol/L), N saline (0.9%) infusion should be replaced with N saline + 5% dextrose containing 20 mmol/L of potassium chloride. The insulin infusion rate is reduced and adjusted according to blood glucose.
7. Seek the underlying cause. Physical examination may reveal a source of infection (e.g. a perianal abscess). Two common markers of infection are misleading: fever is unusual even when infection is present, and polymorphonucleocytosis is present even in the absence of infection. Relevant investigations include a chest X-ray, urine and blood cultures, and an ECG (if severe hyperkalemia). If infection is suspected, broad-spectrum antibiotics are started once the appropriate cultures have been taken.
a. If patient is shocked administer an initial bolus of fluid to correct hypovolaemia. Give bolus of 10ml/kg of normal (0.9%) saline, which may be repeated if necessary. Do not give bolus routinely to avoid cerebral oedema.
b. Then determine an hourly rate (Maintenance + Deficit + Ongoing losses) using N saline to correct deficit + maintenance over 48 hr.
A child's water deficit in mls can be calculated following an estimation of the degree of dehydration expressed as % of body weight (e.g. a 10kg child who is 5% dehydrated has a water deficit of 500mls). The deficit is replaced slowly - e.g. over 48 hours in DKA.
Clinical signs of dehydration:
Categories of dehydration:
There are two major factors that contribute to the pathogenesis of diabetes:
Type 1 diabetes is caused by autoimmune destruction of the beta cells (insulin-producing cells) of the islets of Langerhans. T-cell infiltration of the islets and circulating autoantibodies precede the development of diabetes for months to years. There is an increased frequency of certain HLA types (HLA DR3/DQ2 and DR4/DQ8) in children with diabetes. The HLA genes are located on chromosome 6 and encode HLA molecules on the beta cells.
Environmental factors that are potential candidates in the initiation of autoimmunity or that might act as progression factors are viruses (particularly enteroviruses) and dietary factors (cereals and cow's milk). However, only congenital rubella is a proven environmental trigger and this is a rare cause of type 1 diabetes. The increase in childhood obesity may also account for an earlier presentation of type 2 diabetes due to insulin resistance and beta cell exhaustion but the extent of this contribution to the increasing incidence of type 2 diabetes is unresolved.
Sick days can cause:
1. High blood glucose levels: These are more common during illness - particularly in viral illnesses with fever (e.g. influenza or a bad cold) or in bacterial illnesses (e.g. tonsillitis or ear infections). The blood glucose levels rise as 'stress' hormones are released to help the body cope with illness; however, these stress hormones work against insulin, and the normal insulin given does not work as well (called insulin resistance). Blood glucose levels will often still be high even if the child's appetite is poor because of continuing release of glucose from the liver.
2. Low blood glucose levels: This is likely to occur in stomach and bowel illnesses (gastroenteritis) with nausea, vomiting and especially diarrhoea, but without other general symptoms such as fever. The blood glucose levels are low because the child's appetite is often decreased and the food and drink that is taken is not being well absorbed.
If, during illness, high blood glucose levels are not treated:
The goals of sick day care are to:
KETONES are chemicals in the blood which come from the breakdown of fat. The body makes ketones as an alternative energy source to glucose in some situations. When there are ketones in the blood they will also be found in the urine, and thus a urine test can be used to identify ketones.
Ketones will be produced in diabetes in two situations:
1. When the body is lacking insulin: The blood glucose level will be high, but the body cannot use glucose for energy because of the lack of insulin. Thus fat is broken down to form ketones as an alternative energy supply. This can happen during illness, or when insulin doses are too low or have been missed. When the blood glucose is high, ketones in the blood or urine are a warning sign that the body needs more insulin. If ketones continue to build up, the child can become very sick with ketoacidosis.
2. When supplies of glucose are running low due to fasting or starvation: This can happen in stomach and bowel illnesses with vomiting and diarrhoea. Blood glucose will be normal or low. In this situation more glucose intake is needed, and if this cannot be taken by mouth occasionally a stay in hospital may be needed. Insulin doses should not be omitted, but may need to be lowered.
Typical insulin regimen:
Most children start off on a twice daily regime as outlined below:
In many infants and young children who start on this combination, the short-acting insulin may become unnecessary after a few days or weeks and they may require only a long-acting insulin, especially during the 'honeymoon' phase. Later on a combination will again be needed.
Advice for Amelia's father:
You would advise Amelia's parents that her blood glucose reading is in ideal range (4.2 mmol/L is normal). You would continue on the current dose of insulin and repeat the reading in 4 hours.
Key Components of follow-up:
Support groups for families: