Awareness of hypoglycemia and spectral analysis of heart rate variability in type 1 diabetes

Intermittently scanned continuous glucose monitoring and hypoglycaemia awareness in drivers with diabetes: Insights from the Association of British Clinical Diabetologists Nationwide audit

AIM

Frequent hypoglycaemia results in disruption to usual hypoglycaemic autonomic responses leading to impaired awareness of hypoglycaemia, which is associated with an increased risk of severe hypoglycaemia requiring third-party assistance (SH). The UK Driving and Vehicle Licensing Agency (DVLA) does not permit car driving if they have either a complete loss of hypoglycaemia awareness or more than one SH event a year.

METHODS

The FreeStyle Libre (FSL) Association of British Clinical Diabetologists (ABCD) Nationwide Audit consists of data collected by clinicians during routine clinical work, submitted into a secure web-based tool held within the National Health Service (NHS) N3 network. Analysis of paired baseline and follow-up data for people with type 1 diabetes who also held a driving licence was undertaken.

RESULTS

The study consisted of 6304 people who had data recorded about driving status from 102 UK specialist diabetes centres, of which 4218 held a driving licence: 4178 a group 1, standard licence, 33 a group 2, large lorries and buses, seven a taxi licence; 1819 did not drive. Paired baseline and follow-up data were available for a sub-cohort of 1606/4218. At a mean follow-up of 6.9 months [95% CI (6.8, 7.1)], the Gold score had improved (2.3 ± 1.5 vs. 2.0 ± 1.3 p < .001), and the number of people who experienced an SH episode was also significantly lower (12.1% vs. 2.7%, p < .001).

CONCLUSION

This study suggests that intermittently scanned continuous glucose monitoring may improve impaired awareness of hypoglycaemia and reduce the number of people with type 1 diabetes with a driving licence experiencing a severe hypoglycaemic episode.

Increased risk of death following recurrent ketoacidosis admissions: a Brazilian cohort study of young adults with type 1 diabetes

BACKGROUND

Recurrent DKA (rDKA) remains an acute type 1 diabetes complication even in post-insulin era. This study aimed to analyze the predictors and effects of rDKA on the mortality of patients with type 1 diabetes.

METHODS

Patients hospitalized (n = 231) wih diabetic ketoacidosis (between 2007 and 2018) were included. Laboratorial and clinical variables were collected. Mortality curves were compared in four groups: diabetic ketoacidosis as a new-onset type 1 diabetes (group A), single diabetic ketoacidosis episode after diagnosis of type 1 diabetes (group B), 2-5 diabetic ketoacidosis events (group C), and > 5 diabetic ketoacidosis events during follow-up period (group D).

RESULTS

During the follow-up period (approximately 1823 days), the mortality rate was 16.02% (37/231). The median age at death was 38.7 years. In the survival curve analysis, at 1926 days (5 years), the probabilities of death were indicated by ratios of 7.78%, 4.58%, 24.40%, and 26.63% in groups A, B, C, and D, respectively. One diabetic ketoacidosis episode compared with ≥ 2 events had a relative risk of 4.49 (p = 0.004) of death and > 5 events had 5.81 (p = 0.04). Neuropathy (RR 10.04; p < 0.001), retinopathy (relative risk 7.94; p < 0.01), nephropathy (RR 7.10; p < 0.001), mood disorders (RR 3.57; p = 0.002), antidepressant use (RR 3.09; p = 0.004), and statin use (RR 2.81; p = 0.0024) increased the risk of death.

CONCLUSIONS

Patients with type 1 diabetes with > 2 diabetic ketoacidosis episodes have four times greater risk of death in 5 years. Microangiopathies, mood disorders, and use of antidepressants and statins were important risk factors for short-term mortality.

Hypoglycemia unawareness in type 1 diabetes patients using intermittent continuous glucose monitoring: Identification of risk factors and glycemic patterns

BACKGROUND

Hypoglycemia unawareness designates failure to detect eminent hypoglycemia. Clarke's questionnaire is one of the most used systems to evaluate this problem.

AIMS

To relate Clarke's questionnaire (QQ) results with continuous glucose monitoring data.

METHODS

Application of the questionnaire in a sample of type 1 diabetes mellitus (T1DM) patients using intermittent continuous glucose monitoring (iCGM).

RESULTS

111 T1DM patients were evaluated, 56.8% female, mean age 35.0 ± 12.4 years and mean disease duration 18.8 ± 10.5 years. According to CQ, 13.5% had unawareness, 76.6% awareness and 9.9% indeterminate awareness to hypoglycemia. Those with unawareness had longer disease duration (25.1 ± 10.4 vs 18.2 ± 10.3 for awareness and 14.9 ± 9.9 for indeterminate awareness, p = 0.047), more time below range (10.3 ± 4.9% vs 6.3 ± 5.1 and 6.3 ± 4.8; p = 0.009) and higher mean duration of hypoglycemia (131.7 ± 38.6 vs 116.6 ± 49.6 and 131.7 ± 38.6; p = 0.008). In multivariate analysis, mean duration of hypoglycemia was an independent predictor of CQ results. In a receiver operating curve (AUC 0.746; p = 0.004) a mean duration of hypoglycemia ≥106.5 min showed 84.6% sensitivity/64.4% specificity for unawareness.

CONCLUSIONS

Our sample had a significative prevalence of hypoglycemia unawareness which increased with longer diabetes duration. iCGM data can be indicative of this problem, with a mean hypoglycemia duration ≥106.5 min being suggestive, albeit unspecific.

Rapid glucose rise reduces heart rate variability in adults with type 1 diabetes: A prospective secondary outcome analysis

To investigate differences in heart rate variability (HRV) during oral glucose tolerance tests (OGTTs) in response to the rate of change in glucose and to different glycaemic ranges in individuals with type 1 diabetes. This was a single-centre, prospective, secondary outcome analysis in 17 individuals with type 1 diabetes (glycated haemoglobin 53 ± 6.3 mmol/L), who underwent two OGTTs (after 12 and 36 hours of fasting) investigating differences in HRV in response to rapid glucose increases/decreases and different glycaemic ranges during OGTT. Based on the rate of change in glucose level, the variables heart rate (P < 0.001), square root of the mean standard difference of successive R-R intervals (P = 0.002), percentage of pairs of R-R intervals with >50 ms difference (P < 0.001) and corrected QT interval (P = 0.04) were significantly altered, with HRV particularly reduced during episodes of rapid glucose rises. Glycaemic ranges during OGTT had no impact on HRV (P < 0.05). Individuals with type 1 diabetes showed no changes in HRV in response to different glycaemic ranges. HRV was dependent on the rate of change in glucose, especially rapid increases in glucose level.