1958-LB: Overnight Glycemia’s Relevance to Insulin Resistance (IR) in Type 1 Diabetes (T1D)

IR is a key contributor to cardiovascular disease in T1D but is difficult to measure. The relevance of mean overnight glycemia (MOG) in IR assessments by gold-standard hyperinsulinemic-euglycemic clamps (HEC) in T1D is unclear. We assessed the relationship between pre-HEC MOG and HEC-assessed IR in pubertal adolescents ages 12-19 yrs with T1D.

Each youth underwent admission with variable overnight intravenous insulin infusion titrated with a standardized protocol to a goal blood glucose (BG) of 100-120 mg/dL, followed by an AM HEC with 80mU/m²/min insulin infusion paired with a variable glucose infusion rate (GIR, 20% dextrose infusion, goal BG 95-100 mg/dL). MOG and insulin infusion rates were assessed overnight. Achieved MOG was categorized as ≤100, 101-120, and 121-140 mg/dL. IR was assessed by end-HEC steady-state GIR and free fatty acids (FFA).

80 youth (42 girls, 38 boys) with T1D enrolled (mean age 16 ± 2.1 yrs, HbA1c 8.4 ± 1.6%, T1D duration 6.9 ± 4.0 yrs, BMI 24.0 ± 4.7 kg/m²). Mean BG at end-HEC was 99.0 ± 7.4 mg/dL. Results categorized by MOG category are shown in the Table. As MOG category increased, overnight insulin infusion requirements and end-HEC FFA’s increased and GIR decreased.

In T1D, more difficult to control overnight BG in a controlled setting likely reflects greater overnight IR and HEC whole-body and adipose IR. Future directions include home overnight pump/CGM-based simpler methods for assessing IR in T1D.

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