The Relationship Between CGM-Derived Metrics, A1C, and Risk of Hypoglycemia in Older Adults With Type 1 Diabetes.

OBJECTIVE: Continuous glucose monitoring (CGM) is now commonly used in the management of type 1 diabetes (T1D). The CGM-derived coefficient of variation (CV) measures glucose variability, and the glucose management indicator (GMI) measures mean glycemia (previously called estimated A1C). However, their relationship with laboratory-measured A1C and the risk of hypoglycemia in older adults with T1D is not well studied. RESEARCH DESIGN AND METHODS: In a single-center study, older adults (age ≥65 years) with T1D wore a CGM device for 14 days. The CV (%) and GMI were calculated, and A1C and clinical and demographic information were collected. RESULTS: We evaluated 130 older adults (age 71 ± 5 years), of whom 55% were women, 97% were White, diabetes duration was 39 ± 17 years, and A1C was 7.3 ± 0.6% (56 ± 15 mmol/mol). Participants were stratified by high CV (>36%; n = 77) and low CV (≤36%; n = 53). Although there was no difference in A1C levels between the groups with high and low CV (7.3% [56 mmol/mol] vs. 7.3% [53 mmol/mol], P = 0.4), the high CV group spent more time in hypoglycemia (<70 mg/dL and ≤54 mg/dL) compared with the group with low CV (median 31 vs. 84 min/day, P < 0.0001; 8 vs. 46 min/day, P < 0.001, respectively). An absolute difference between A1C and GMI of ≥0.5% was observed in 46% of the cohort. When the A1C was higher than the GMI by ≥0.5%, a higher duration of hypoglycemia was observed (P = 0.02). CONCLUSIONS: In older adults with T1D, the use of CGM-derived CV and GMI can better identify individuals at higher risk for hypoglycemia compared with A1C alone. These measures should be combined with A1C for better diabetes management in older adults with T1D.

Examining the Relationship Between Pre- and Postprandial Glucose Levels and Insulin Bolus Timing Using Bluetooth-Enabled Insulin Pen Cap Technology and Continuous Glucose Monitoring.

Background: Timing of insulin administration in persons using multiple daily injections (MDI) is self-reported. New technology enabling tracking and logging of insulin doses, combined with continuous glucose monitoring (CGM), may provide insight into the relationship between insulin administration and glucose levels. Methods: We performed a prospective observational study using Bluetooth-enabled pen caps, along with CGM, in participants with type 1 diabetes (T1D) on MDI to objectively assess the relationship between the timing of insulin administration and its impact on pre- and postprandial glucose levels for a 2-week period. Results: We evaluated 50 participants (age 40.3 ± 19 years; A1c 8.2% ± 1.5%, duration of T1D 20 ± 15 years). Thirty-seven percent of total boluses resulted in persistent hyperglycemia (glucose >180 mg/dL 3 h postprandially), while 10% resulted in clinically significant hypoglycemia (glucose <55 mg/dL 3 h postprandially) on CGM. Preprandial glucose levels at the time of the bolus did not correlate with postprandial glucose levels. Late boluses, defined as a rise in glucose of ≥50 mg/dL before a bolus, were seen two times/patient/week. Missed boluses, defined as a rise in glucose of ≥50 mg/dL without a bolus within 2 h, occurred 17 times/patient/week. Late and missed boluses were associated with worse glycemic control (A1c; R2 = 0.1, P = 0.02; R2 = 0.1, P = 0.02). Conclusions: The use of Bluetooth-enabled pen caps, with CGM, in persons with T1D on MDI can illustrate the relationship between insulin bolus timing and postprandial glucose. These data may help clinicians and patients understand the impact of timing of insulin doses on glucose levels and glycemic control.

Nonadherence to Insulin Therapy Detected by Bluetooth-Enabled Pen Cap Is Associated With Poor Glycemic Control.

OBJECTIVE: To objectively evaluate adherence to timing and dosing of insulin by using Bluetooth pen caps and examine factors related to adherence. RESEARCH DESIGN AND METHODS: Bluetooth-enabled insulin pen caps were used in younger (ages 18-35 years) and older (ages ≥65 years) adults on two or more insulin injections per day. RESULTS: We evaluated 75 participants with diabetes, 42 younger (29 ± 4 years) and 33 older (73 ± 7 years). Nonadherence was found in 24% of bolus (Apidra) doses and 36% of basal (Lantus) doses. We divided participants into tertiles on the basis of overall adherence, with the most adherent tertile having 85% dose adherence compared with 49% in the least adherent tertile (P < 0.001). Participants in the most adherent tertile had better glycemic control than those in the least adherent tertile (7.7 ± 1.1% [61 ± 12 mmol/mol] vs. 8.6 ± 1.5% [70 ± 16.4 mmol/mol], P < 0.03). CONCLUSIONS: Nonadherence to insulin dosing and timing can be objectively assessed by Bluetooth pen caps and is associated with poor glycemic control.