Diabetes Ketoacidosis (DKA) Diagnostic Parameters Are Not The Same
Diabetes Ketoacidosis (DKA) is a life-threatening complication of insulin-insufficient diabetes. When we lack the ability to use carbohydrates for energy (due to lack of insulin), the body will break down fats for energy. The byproduct of this breakdown is called a ketone. Many people are diagnosed in a state of DKA. However, DKA can happen at any time during insulin use if insulin levels drop too low for too long or if the body is under enough physical stress to produce its own ketones or raise insulin needs beyond the insulin in the body.
We would think that a life-threatening diagnosis like DKA would come with clear clinical guidelines for diagnosis. However, this is not so.
In a recent interview article by Dr. Brook Andrews in AACC’s September clinical laboratory update we see that both internationally and within the US the criteria for appropriate diagnosis are wide. In the US the ADA diagnostic parameters are: serum glucose >250 mg/dL, arterial pH <7.3, serum bicarbonate <18 mmol/L, ketonuria or ketonemia, and anion gap >10.
However, Diabetes UK does not include the anion gap and 2018 Diabetes Canada Clinical Practice Guidelines state that “there are no definitive criteria for diagnosis of DKA.”.
The Canadian guidelines may be the closest to the truth as it is possible3 to be in DKA with a BG below 250. The Anion Gap is used to discern between DKA and Hyperosmolar Hyperglycemic Syndrome (HHS) With so much clinical diversity in DKA diagnosis it is easy for someone with diabetes to arrive in the Emergency Department and be misdiagnosed.
I advise patients on insulin to clearly report their ketone level to emergency personnel and specifically ask that their bicarb and pH be checked if they are having digestive symptoms or have shown any change in mentation. It is also important that all of these values be monitored if someone on insulin is hospitalized for an infection.
In the article, the focus is on what method of ketone screening is most effective in the clinical setting. But two clear conclusions are that ketone testing is a MUST for people on insulin and the second is that blood-based ketone screening is more precise than urine screening both in the clinic and at home.
Urine-based test dipstick tests have the benefits of being the least intrusive making them appropriate for diabetes risk screening for those not yet diagnosed in clinical settings. Urine dipsticks are also the most readily available option available at almost any pharmacy over the counter. But we never want to wait until we are in need to purchase test strips, we should have them on hand at home in case of sick days. Dipsticks are also the cheapest option for testing (costing roughly $0.10usd each). However, since this is an item that is not used in an ongoing way ketone meter strips are a very small cost for a one-year supply. The biggest problems with urine-based test strips are that they are subjective, and not timely. Dipsticks cause a chemical reaction on the strip when in the presence of acetone-based ketones, which make up a very small amount of overall ketones. Because of the delay in timing of these waste products from the blood to the urine, the results are actually reflective of what blood ketone levels were hours before testing rather than in the moment.
Meanwhile, blood-based testing measures levels of beta-hydroxybutyrate (BHB) ketones which make up 80% of ketones, directly in the blood sample in the moment. Blood-based ketones also give an objective measurement that is not open to color interpretation. Urine dipsticks require that the user match the result to a color guide on the bottle which leads to inaccurate interpretation and makes them unusable by people with colorblindness. BHB ketone testing is also the only approved method for people without the ability to urinate, chronic kidney failure or other renal impairments as they may not effectively show ketones in their urine, again leading to false negatives.
Urine ketone strips are good for emergencies or carrying when you can not rely on a meter. There are many brands of urine dipsticks. Never use dipsticks after their expiration date and it is recommended to discard a vial 6 months after opening to ensure accuracy. Keep them stored in a cool dry space and keep the vial closed when not in use. Be sure to keep the dipstick test section submerged for the listed time.
Blood-based meters that are FDA-approved include the Precision Xtra by Accu check and the Optium Beta from Freestyle. Strips cost roughly $1 each. The meters cost roughly $40-50 and can be covered as durable medical equipment under insurance but are available over the counter. These work just like a glucometer. Strips come individually wrapped and are subject to expiration dates.
Prevention of DKA and accessibility to ketone testing supplies are critical to a healthy life with diabetes. If your prescriber has not provided both ASK!