Type 2 diabetes mellitus (T2DM) is estimated to account for 10-45% of incident pediatric diabetes cases. Our objective was to characterize the metabolic defects underlying T2DM in adolescents and young adults. We conducted a cross-sectional study of islet function and insulin sensitivity in 16 adolescents with T2DM and 13 obese (OB) and 13 lean (LN) age-matched nondiabetic subjects at a University Medical Center. We provided oral and iv glucose tolerance tests. We measured insulin and glucagon levels, insulin sensitivity, acute insulin responses to iv glucose, and the ratio of proinsulin to immunoreactive insulin. The diabetic subjects had elevated fasting insulin levels and significantly reduced insulin sensitivity (P < 0.05). The acute insulin response to iv glucose was comparable in the T2DM and LN groups (P < 0.05 for the OB vs. LN and T2DM), but insulin secretion adjusted for insulin resistance, the disposition index, was severely impaired in the diabetic subjects (P < 0.05 for the T2DM vs. LN and OB). The ratio of proinsulin to immunoreactive insulin did not differ among the three groups in the basal or stimulated state. Plasma glucagon levels were comparable before and after ingestion of glucose. These findings demonstrate that diabetic adolescents have significant insulin resistance, even compared with subjects of similar obesity and body fatness, and impaired insulin secretion relative to their degree of insulin resistance. However, the adolescent diabetic subjects retained a first-phase insulin response to glucose that was comparable to lean controls and did not have hyperproinsulinemia or hyperglucagonemia.

Objective: To assess the degree, duration, mean absolute relative difference (MARD), and error analysis of discrepant values per continuous glucose monitoring (CGM) systems after hydroxyurea (HU) administration. Research Design and Methods: Inpatient glucometer and CGM data from 16 total pancreatectomy/islet autotransplantation patients using Dexcom Professional G4 and 12 patients using Dexcom G6 were analyzed after daily dosing with HU. Timing of HU dosing and median of 9.5 days of sensor and glucometer values were assessed per patient. Results: A large positive elevation of sensor readings was identified after HU dosing. The greatest discrepancy between glucometer and sensor readings occurred 0.5–2 h after HU administration [G4 (mean 3.0 mmol/L, median 2.4 mmol/L, MARD 55%), G6 (mean 4.2 mmol/L, median 4.6 mmol/L, MARD 91%)]. The discrepancy was <1.1 mmol/L, mean (−0.5 mmol/L) and median (−0.5 mmol/L), MARD 14% (G4) and <1.1 mmol/L, mean (0.3 mmol/L) and median (0.3 mmol/L), MARD 17% (G6), by 6 h after administration. Error analysis with the G6 system found 94% of pairs in clinically acceptable range by 6–9 h after HU administration. Aspirin, also given once daily, did not result in glucose value discrepancy with the G6 system but variability was observed with the G4 system. Conclusions: There was marked elevation of sensor glucose readings compared with glucometer values [up to 13.9 mmol/L (G4), 13 mmol/L (G6)] from 0.5 to 6 h after HU administration. It is important to counsel a patient using a Dexcom CGM system and HU therapy on this finding and to advise reliance on glucometer testing for accurate glucose assessment up to 6–9 h after HU administration.

Hyperglycemia is detrimental to postoperative islet cell survival in patients undergoing total pancreatectomy with islet autotransplantation (TPIAT). This makes continuous glucose monitoring (CGM) a useful management tool. We evaluated the accuracy of the Dexcom G6 CGM in pediatric intensive care unit patients following TPIAT. Twenty-five patients who underwent TPIAT had Dexcom G6 glucose values compared to paired serum glucose values. All paired glucose samples were obtained within 5 minutes of each other during the first seven days post TPIAT. Data were evaluated using mean absolute difference (MAD), mean absolute relative difference (MARD), %20/20, %15/15 accuracy, and Clarke Error Grid analysis. Exclusions included analysis during the CGM “warm-up” period and hydroxyurea administration (known drug interference). A total of 183 time-matched samples were reviewed during postoperative days 2–7. MAD was 14.7 mg/dL and MARD was 13.4%, with values of 15.2%, 14.0%, 12.1%, 11.4%, 13.2% and 14.1% at days 2, 3, 4, 5, 6 and 7, respectively. Dexcom G6 had a %20/20 accuracy of 78%, and a %15/15 accuracy of 64%. Clarke Error Grid analysis showed that 77% of time-matched values were clinically accurate, and 100% were clinically acceptable. The Dexcom G6 CGM may be an accurate tool producing clinically acceptable values to make reliable clinical decisions in the immediate post-TPIAT period.