Severe hypoglycemia, impaired awareness of hypoglycemia, and self-monitoring in adults with type 1 diabetes: Results from Diabetes MILES—Australia
Introduction
Severe hypoglycemia, defined as requiring assistance from another person for recovery, is one of the most common, feared and challenging complications of type 1 diabetes (Cryer, 2002). Severe hypoglycemia has an annual prevalence of 30% (Frier, 2014), ranging from 22% in those with a type 1 diabetes duration of less than five years to 46% in those with long (over 15 years) duration (UK Hypoglycaemia Study Group, 2007). Timely recognition of subjective sensations/warnings of low glucose levels is necessary for detection and self-treatment of mild hypoglycemia to prevent severe hypoglycemia. Hypoglycemic symptoms are classified as autonomic, neuroglycopenic and general malaise (Deary, Hepburn, MacLeod, & Frier, 1993). Over time, the profile and intensity of symptoms change (McAulay, Deary, & Frier, 2001), leading to impaired awareness of hypoglycemia (IAH). This syndrome is associated with impaired glucose counter-regulation, resulting in a lower glucose threshold for symptom occurrence (Graveling & Frier, 2010). IAH affects 20%–25% of unselected type 1 diabetes clinic populations (Geddes, Schopman, Zammitt, & Frier, 2008), rising to 50% after 25 years’ duration (Pramming, Thorsteinsson, Bendtson, & Binder, 1991). IAH is associated with a six-fold increased risk of severe hypoglycemia (Geddes et al., 2008).
While a recent population-based cohort study demonstrated that severe hypoglycemia rates are reducing in Australian children and adolescents with type 1 diabetes (O'Connell, Cooper, Bulsara, Davis, & Jones, 2011), few Australian studies have focused on rates of problematic hypoglycemia in adults. In an unselected clinical population of adults attending three specialist type 1 diabetes centers in Melbourne, 21% had IAH and 19% had experienced severe hypoglycemia in the past six months (Hendrieckx et al., 2014), consistent with data published for clinical populations (Geddes et al., 2008, Gold et al., 1994, Olsen et al., 2014). Furthermore, IAH was associated with a 10-fold increase in severe hypoglycemia (Hendrieckx et al., 2014). However, there have been no national cohort studies and little is known about self-monitoring of blood glucose (SMBG) practices in this group in Australia.
The aim of the current study was to investigate the self-reported prevalence of severe hypoglycemia and IAH in a large, Australian national cohort. In addition, we considered two research questions: compared to adults with intact hypoglycemic awareness, 1) do those with IAH perceive and treat hypoglycemia symptoms at different blood glucose levels? and 2) do they check their blood glucose levels more frequently to avoid severe hypoglycemia?
Section snippets
Research design and methods
We analyzed data from the Diabetes MILES—Australia 2011 study, a large national survey about what it is like to live with type 1 or type 2 diabetes. Surveys were posted to 15,000 randomly selected National Diabetes Services Scheme (NDSS) registrants, aged 18–70 years. The study was advertised widely and could also be completed online. In total, 3338 eligible respondents took part; 42% with type 1 diabetes. All states and territories of Australia were represented. Full details of survey methods
Participant characteristics
Of 650 eligible respondents, 98% (n = 636) completed the Gold score (IAH) and 94% (n = 611) the severe hypoglycemia frequency item; eight participants did not respond to either item and were excluded. Participant demographic and clinical characteristics (overall, by severe hypoglycemia and by IAH status) are detailed in Table 1.
Mean age and diabetes duration were 41 ± 13 and 15 ± 13 years respectively. Thirty-eight percent (n = 246) were men, 41% (n = 251) had a university or higher education qualification,
Conclusion
In this large national survey, adults with type 1 diabetes reported experiencing hypoglycemia (mild or severe; day or night) approximately twice per week on average. One in five had at least one severe hypoglycemic event in the past six months and one in five had IAH. Severe hypoglycemia was six-fold higher in people with IAH than in those with intact hypoglycemia awareness. These self-reported prevalence data for both severe hypoglycemia and IAH are consistent with previous reports in
Funding
The Diabetes MILES—Australia 2011 survey was supported by a National Diabetes Services Scheme (NDSS) Strategic Development Grant and by an unrestricted educational grant from Sanofi. The NDSS is an initiative of the Australia Government administered by Diabetes Australia.
Acknowledgments
We thank the people with diabetes who participated in the Diabetes MILES—Australia Study.
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Authors have no conflict of interest to declare.