Our contemporary study of EMS requiring hypoglycemia confirms that such episodes place significant burden on medical resources and result in long-term morbidity and mortality. Other population-based estimates of hypoglycemia requiring EMS were reported in 2003 or earlier when therapeutic options were limited. Non-DM patients who experienced hypoglycemia constituted 16% of the sample, higher than other reports (6 and 3% respectively).19,20
Both of these studies are more than 7 years old, at a time when therapeutic options were limited. Further, the studies had small sample size and short study periods, with non-DM patients being removed from further analysis.
In our cohort, non-DM patients were at increased risk for mortality compared to DM patients. These patients were more likely to require ERT and hospitalization. This could be due to the more severe nature of the underlying disease. In our study, chronic comorbidities that could cause hypoglycemia were higher in the DM cohort. Because of inability to grade illness severity in outpatients, it is difficult to compare mortality between non-DM and DM cohorts by matching for severity of sickness. Data from inpatient studies have shown association of hypoglycemia with higher mortality but these data were restricted to patients admitted for myocardial ischemia who developed hypoglycemia during the same hospitalization.21
Such evidence is missing for outpatient populations. Thus, hypoglycemia in non-DM outpatient settings may also need to be managed expeditiously with a critical clinical pathway.
The DM group constituted 81% of the cohort, and frequency of calls was 0.75 patient−1
. Emergency medical services were mostly required by T2DM patients (55%), which is expected because of the larger T2DM population. But, the frequency of calls among T2DM patients was lesser than for T1DM patients (0.63 patient−1
and 0.87 patient−1
, respectively). Frequency of EMS requiring hypoglycemia in the DM, T1DM, and T2DM cohorts was lesser than reports that were published up until 2003; these were limited by small cohort sizes and shorter follow-up periods.5,13
T2DM patients were predominantly on insulin (MDI > simple insulin) followed by SFUI, which is similar to a report from 2003.19
Thus, despite development of insulin analogs, insulin continues to constitute the major risk factor for hypoglycemia in T2DM patients; however, most of the patients still use the traditional MDI and standard injeciton therapy, and data about hypoglycemia with pumps and especially sensor-augmented pumps are in their early years. We also observed hypoglycemia in 6 subjects (5 T2DM, 1 T1DM status postpancreas transplantation) on no antihyper-glycemic therapy. Medical records were complete and reviewed exhaustively to eliminate the possibility of ascertainment error.
Patients with T1DM placed more multiple calls compared with the others. Repeat calls in the DM cohort were comparable to similar reports (23 and 26%, respectively).20,22
One of these studies had more patients on insulin (more details not provided) compared to our cohort, while the other study provided limited details about the type of antihyperglycemic treatment. Also, these studies did not define the size of the T1DM and T2DM groups, which can affect the burden of repeated calls. Repeat calls were higher in the T1DM cohort when compared with a similar report described in 1999 (26%).5
Thus, despite development of new insulin delivery devices, CGM, and sensor-augmented insulin delivery devices, repeated calls may have increased since earlier reports. Patients with T1DM had a longer duration of DM compared with T2DM patients. Association of multiple calls with increasing duration of DM in T1DM patients has been reported.5
An additional risk factor for multiple calls by T1DM patients is a history of prior episodes.13,23
This does not seem to have changed despite the more sophisticated insulin delivery and CGM available since earlier reports. Unfortunately, subjects with repeated severe hypoglycemia have been systematically excluded from prospective studies of CGM and insulin delivery devices.8,24
Prospective studies enrolling such patients may decrease morbidity.
Average age at first episode was comparable between TIDM and non-DM patients, but higher in T2DM patients. No difference was seen in gender distribution of calls among the three cohorts. Earlier data about gender distribution of EMS requiring hypoglycemia is limited among T2DM and non-DM patients but our data in T1DM patients are similar to an earlier report.13
Treatment of hypoglycemia at the scene by paramedics can cut down the cost of ERT and hospitalization and at the same time preserve high patient satisfaction.25
However, in our cohort, more than half of the patients required ERT (60%). Among DM patients, ERT was higher than in earlier reports but later data are not available.13,20
Half of the transported patients were hospitalized for further treatment. Hospitalization among DM patients (30%) was comparable to a study by Leese and colleagues (28%) but higher than other similar reports.6,13,20
ERT rates per ambulance calls for the entire sample increased from 59% in 2003 to 79% in 2009 (
), which could be because of the more severe nature of hypoglycemic episodes or other factors such as changes in local clinical practice, EMS personnel, reimbursement structure, fear of litigation, or other reasons. Prospective studies with deconstruction of events in real time would be vital to reduce morbidity and mortality in these high-risk populations. Ginde and colleagues6
observed no change in ERT per 1,000 DM patients with or total ER visits between 1993–2005 without involving Non-DM patients but did not report data about EMS. Further, this large study did not report morbidity in different types of DM patients or details of DM therapy, and therefore has limited value regarding planning of interventions to change trends and improve outcomes.
A large number of patients (26%) died during the study period with respiratory illnesses as the main cause of mortality followed by cardiovascular diseases. It is difficult to establish the cause and effect association from the temporal relationship of hypoglycemia and death. Hypoglycemia-associated mortality in our cohort (3%) was higher than a similar report in 2003.19
Fifteen percent of patients died during the same hospitalization with the main reasons being respiratory illness and sepsis. Causes of death after EMS requiring hypoglycemia have not been reported in a population-based study.
This is the first population-based study of EMS requiring hypoglycemia with a detailed description of incidence, burden on medical resources utilization, and mortality among DM and non-DM patients. Non-DM patients have been excluded from the earlier studies; however, these patients may need to be managed with a critical clinical pathway due to worse outcomes compared to DM patients. Also, our study provides updated information about the population burden of EMS requiring hypo-glycemia. Limitations of our study include slight inflation of hypoglycemia incidence due to a large transient population visiting the Mayo Clinic who are at risk for hypo-glycemia. Besides severity of hypoglycemia, ambulance calls for a patient could be driven by reasons such as the caller's familiarity with hypoglycemia, availability of glucagon, past frightening experiences with severe hypoglycemia, and emotional reactions to events such as vehicular accidents, etc.
In conclusion, hypoglycemia requiring EMS places significant burden on medical resources and is associated with significant long-term morbidity and mortality. Hypoglycemia in non-DM patients was more severe requiring higher ERT and hospitalization and had higher mortality compared to DM patients. Prospective strategies need to be developed and evaluated that capture hypoglycemia promptly and include an integrated approach for prevention of such episodes, resulting in alleviation of patient discomfort, decreased burden on hospital services, improved long-term outcomes, and decreased morbidity and mortality.