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11-13-2020 | Disordered eating | News

Very high blood glucose may hint at disordered eating in type 1 diabetes

Eleanor McDermid

medwireNews: Women with type 1 diabetes and a history of disordered eating spend markedly more time in level 2 hyperglycemia than women without eating disorders, show the results of a small continuous glucose monitoring (CGM) study.

Women with eating disorders spent around four times as long with their blood glucose above 13.9 mmol/L (250 mg/dL) as those who had type 1 diabetes but no history of disordered eating, report Marietta Stadler (King's College London, UK) and co-researchers.

“Disordered eating is a condition that thrives in secrecy and people tend not to report their symptoms and behaviours in clinics; therefore, diabetes clinicians’ knowledge of diabetes self-management behaviour in a person with type 1 diabetes is scarce,” they write in Diabetic Medicine.

They suggest: “Characterization of glycaemic changes could serve as a surrogate marker for early identification of this condition.”

The team’s study involved 13 women with type 1 diabetes and a historic or ongoing eating disorder, namely anorexia nervosa in five cases, bulimia nervosa in three, binge eating disorder in two, and a history of insulin restriction for weight loss in three. The women underwent blinded CGM for a week and were encouraged to keep a diabetes diary, detailing meals, emotions and behaviors, insulin doses, glucose measurements, and exercise.

These women spent significantly less time in range than 10 women without disordered eating, with glucose levels being within the range of 3.9–10.0 mmol/L (70–180 mg/dL) for a median of 42.6% versus 69.7% of the time.

The researchers found this was accounted for by a marked increase in time above range, at a median of 49.8% versus 25.6%, including a “strikingly different” fourfold increase in time spent with levels exceeding 13.9 mmol/L, at 21.3% versus 5.0%. This means that the women with disordered eating were spending more than 5 hours per 24 in level 2 hyperglycemia, compared with 1.2 hours for those without eating disorders.

Glucose variability was significantly higher in women with disordered eating when measured as the standard deviation (SD), but not as the coefficient of variability (%CV), which Stadler and team explain is because the women with eating disorders had an increase in both their mean glucose and SD, meaning that %CV, which is calculated from both, was unaffected.

They note that most CGM software reports both variables but the sole available flash glucose monitor (the Freestyle Libre) currently only provides %CV.

Women with disordered eating reported a higher frequency of negative emotions than those without, occurring when self-monitored blood glucose readings were greater than 15 mmol/L (270 mg/dL), and they also experienced more physical symptoms at these high levels.

“It was interesting that negative emotions were high only when the glucose value was visible (capillary glucose) and not when it was high on blinded CGM (sensor glucose),” say the researchers.

They note that these negative emotions can lead to inappropriate self-care behaviors such as a “rage bolus” when blood glucose is very high, leading to hypoglycemia and binging on restricted foods without insulin to raise glucose again. This pattern was somewhat reflected in a higher percentage of rising and falling sensor glucose trends for the women with disordered eating versus those without, says the team.

“We believe that early clinical conversations have a major impact on how people view each blood glucose value,” write Stadler and colleagues.

“The use of ‘time in range’, identified by people with diabetes as a key metric, as opposed to strict target ranges, is a move in the right direction as this gives people with diabetes the ‘permission’ to be ‘out-of-range’ for a certain period.

“Thus, a glucose value outside the range may not be immediately seen as a failure, resulting in inappropriate insulin doses.”

medwireNews is an independent medical news service provided by Springer Healthcare Ltd. © 2020 Springer Healthcare Ltd, part of the Springer Nature Group

Diabet Med 2020; doi:10.1111/dme.14446

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