It appears to be common practice in many EMS systems for providers to obtain a blood glucose level on virtually every patient during initial assessment. Many would consider a blood glucose level as the fifth vital sign after blood pressure, pulse rate, respiratory rate and SpO2. The blood glucose level is often obtained at the time of an IV catheter placement. For the most part, blood glucose levels are normal. Thus, one must ask why do we measure a blood glucose level in virtually all prehospital patients?
In patients with diabetes, hypoglycemia can have serious deleterious effects. Generally speaking, hypoglycemia is defined as a blood glucose reading of less than 55-60 mg/dL (3.1-3.3 mmol/L). Patients with diabetes who have taken an excessive amount of insulin, or taken a standard amount of insulin but failed to ingest an adequate number of calories, can develop hypoglycemia.
This can cause numerous side effects including altered mental status, weakness, sweet enough, nausea, vomiting and even unconsciousness. Hypoglycemia is more common in Type 1 diabetes (which requires use of insulin) than Type 2 diabetes where patients augment their oral diabetic agents with insulin. Once detected, the condition can be treated with intravenous glucose, oral glucose or the injection of glucagon.
More commonly, patients with diabetes have markedly elevated blood sugar levels (hyperglycemia). These primarily occur when patients do not adhere to the diabetic management regimen. There are three types of diabetes. Type 1 diabetes mellitus (T1DM) occurs when the beta cells in the endocrine pancreas produce little or no insulin.
Patients with T1DM must use insulin. Patients with Type 2 diabetes mellitus (T2DM), which accounts for about 90-95% of diabetes cases, occurs when the body’s cells stop responding to insulin (insulin resistance) or the beta cells are unable to produce sufficient amounts of insulin for daily activities. Gestational diabetes mellitus (GDM) is diagnosed by detecting hyperglycemia while pregnant. Blood glucose levels in GDM usually normalize following birth but these patients are prone to develop T2DM later in life.1
In terms of hyperglycemia, patients with T1DM are more likely to develop diabetic ketoacidosis (DKA). Patients with T2DM tend not to develop DKA but do develop hyperosmolar hyperglycemic state (HHS). Unlike hypoglycemia, these two conditions take some time to develop and the onset is usually slow. It is uncommon for patients with T2DM to develop hypoglycemia unless they are also using insulin or stop virtually all caloric intake.
Furthermore, there is a limit to the sensitivity and accuracy of point-of-care glucose testing when patients are markedly hyperglycemic. With extremely high blood glucose levels, the devices generally will not work or simply register the patient’s blood glucose level as “high.” From a prehospital care standpoint, the primary treatment for both DKA and HHS is to administer IV fluids. It is fairly straightforward.
In the overall scheme of things, true hypoglycemia in persons without diabetes is uncommon. In a recent prehospital study of 707,417 EMS responses in Helsinki, Finland, 15,158 (2.1%) of patient had blood glucose measured in the prehospital setting. Of those, only 910 (0.12%) of cases of documented hypoglycemia using a blood glucose level of ≤ 54 mg/dL (3.0 mmol/L) to define hypoglycemia occurred in patients without diabetes.
When a blood glucose level of ≤ 70 mg/dL (3.9 mmol/L) was used to define hypoglycemia, 3,856 (0.54%) of patients without diabetes were found to have hypoglycemia. This was most commonly seen in patients with alcohol abuse, hypothermia, malnutrition, intoxication and infection.2 For patients who are critically-ill (ICU patients), maintenance of a blood glucose level between 70-140 mg/dL has been associated with increased survival in patients without diabetes.3
Prehospital point-of-care glucose testing is an important skill. However, it should only be used in patients who have a realistic risk of hypoglycemia. Certainly, all patients with diabetes (or patients with diabetic signs and symptoms) should have their blood glucose measured. Also, any patient who has altered mental status, seizures, pregnancy, alcohol intoxication, alcohol use disorder, hypothermia, malnutrition, and/or infection/sepsis warrant immediate blood glucose measurement.
Patients who are fully alert (non-intoxicated) and people without diabetes probably do not need immediate blood glucose measurement. More importantly, we must get away from nonsensical EMS protocols that treat prehospital medicine as a linear process (A-B-C-D). Sometimes, you must address C before A (non-linear thinking).
Thus, we need EMS personnel to be critical thinkers. Solve the problem using your knowledge and experience, and don’t rely on some archaic protocol that forces you to do A before you can do B. It is interesting to note that prehospital personnel in the Finnish study cited above only checked blood glucose levels in 2.1% of patients encountered. I would guess that the number of prehospital patients in the United States who get point-of-care glucose testing is many times higher than that. Common sense must prevail!
1. Diabetes.org [Internet]. Arlington (VA). [cited 2020 Jan 8]. Available from: https://www.diabetes.org/resources/for-students/common-terms.
2. Vihonen H, Kuisma M, Nurmi J. Hypoglycaemia without diabetes encountered by emergency medical services: a retrospective cohort study. Scand J Trauma Resusc Emerg Med. 2018;26(1):12.
3. Krinsley JS, Preiser JC. Time in blood glucose range 70 to 140 mg/dl >80% is strongly associated with increased survival in non-diabetic critically ill adults. Crit Care. 2015;19:179.