Abstract
Flash Glucose Sensor Monitoring for patients with endogenous hyperinsulinaemic hypoglycaemia
Background:
Flash glucose monitoring systems (FGS) have recently been introduced and measure interstitial glucose using an amperometric electrochemical sensor assay, and are increasingly used to provide a convenient means to monitor levels on a minute-by-minute basis over two weeks in ambulatory patients with diabetes. Although continuous glucose monitoring systems have been previously used in patients with insulinoma,(1) to our knowledge, FGS use has only been described once previously in an adult patient with an insulinoma.(2) Here, we describe use of this system in 6 patients with confirmed endogenous hyperinsulinaemic hypoglycaemia, especially for the critical nocturnal period.
Methods and patients:
FGS data obtained over each 2-week monitoring was reviewed in 6 patients seen between 2018 and 2019: 5 had a biochemically proven insulinoma and 1 had Hirata’s syndrome. In 4 patients, follow-up readings were obtained after adjustment of glucose-raising medication: two on octreotide, one on diazoxide and one on diazoxide and dexamethasone.
Results:
Median age was 63 years (range 37–83). In the 4 patients with more than one 2-week FGS assessment comparison between first and last readings demonstrated that the average duration of hypoglycaemia (<4mmol/L) 126, 171, 173 and 282 minutes improved to 46, 128, 30 and 0 minutes, respectively. The percentage of glucose readings below target (<4mmol/L) improved from 8%, 58%, 4%, and 47% to 1%, 39%, 0%, and 0%, respectively. The mean glucose was 5.9, 3.9, 7.8, and 4.4 mmol/L, which improved to 10.9, 5.0, 7.9, and 7.5 mmol/L respectively. The lowest average glucose was nocturnal (22:00-06:00) (5.8, 3.3, 6.5, and 4.1 mmol/L) which showed significant improvement after adjustment of medications (11.3, 4.2, 7.2, and 5.7 mmol/L). At least 2 of these 4 patients had well documented impaired awareness of hypoglycaemia based on diminished classical adrenergic symptoms. Among the two patients who had only one 2-week FGS assessment, one went on to have curative successful surgery and the second patient who had Hirata’s syndrome did not have significant detectable hypoglycaemia.
Conclusion:
FGS is a convenient tool that may be used to monitor and adjust therapy in patients with endogenous hyperinsulinism. In carefully selected patients, FGS may allow domiciliary glycaemic management avoiding the need for hospital admission for monitoring purposes.
References:
1. Munir, Alia et al. “Continuous glucose monitoring in patients with insulinoma.” Clinical Endocrinology vol.68,6 (2008): 912–918
2. Sugawa, Taku et al. “Hypoglycemia Unawareness in Insulinoma Revealed with Flash Glucose Monitoring Systems.” Internal medicine (Tokyo, Japan) vol. 57,23 (2018): 3407–3412
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