title: Diurnal pattern of insulin action in type 1 diabetes: implications for a closed-loop system.
abstract: We recently demonstrated a diurnal pattern to insulin action (i.e., insulin sensitivity [SI]) in healthy individuals with higher SI at breakfast than at dinner. To determine whether such a pattern exists in type 1 diabetes, we studied 19 subjects with C-peptide-negative diabetes (HbA1c 7.1 ± 0.6%) on insulin pump therapy with normal gastric emptying. Identical mixed meals were ingested during breakfast, lunch, and dinner at 0700, 1300, and 1900 h in randomized Latin square of order on 3 consecutive days when measured daily physical activity was equal. The triple tracer technique enabled measurement of glucose fluxes. Insulin was administered according to the customary insulin:carbohydrate ratio for each participant. Although postprandial glucose excursions did not differ among meals, insulin concentration was higher (P < 0.01) and endogenous glucose production less suppressed (P < 0.049) at breakfast than at lunch. There were no differences in meal glucose appearance or in glucose disappearance between meals. Although there was no statistical difference (P = 0.34) in SI between meals in type 1 diabetic subjects, the diurnal pattern of SI taken across the three meals in its entirety differed (P = 0.016) from that of healthy subjects. Although the pattern in healthy subjects showed decreasing SI between breakfast and lunch, the reverse SI pattern was observed in type 1 diabetic subjects. The results suggest that in contrast to healthy subjects, SI diurnal pattern in type 1 diabetes is specific to the individual and cannot be extrapolated to the type 1 diabetic population as a whole, implying that artificial pancreas algorithms may need to be personalized.
authors: Department of Endocrinology, Mayo Clinic, Rochester, Minnesota.
authors: Ling
authors: L
authors: Hinshaw
authors: Chiara
authors: C
authors: Dalla Man
authors: Debashis K
authors: DK
authors: Nandy
authors: Ahmed
authors: A
authors: Saad
authors: Adil E
authors: AE
authors: Bharucha
authors: James A
authors: JA
authors: Levine
authors: Robert A
authors: RA
authors: Rizza
authors: Rita
authors: R
authors: Basu
authors: Rickey E
authors: RE
authors: Carter
authors: Claudio
authors: C
authors: Cobelli
authors: Yogish C
authors: YC
authors: Kudva
authors: Ananda
authors: A
authors: Basu
mesh_terms: D000328:Adult; D001786:Blood Glucose; D002096:C-Peptide / Q000097:blood; D003922:Diabetes Mellitus, Type 1 / Q000097:blood* / Q000188:drug therapy; D005260:Female; D006801:Humans; D007004:Hypoglycemic Agents / Q000627:therapeutic use; D007328:Insulin / Q000097:blood*; D061267:Insulin Aspart / Q000627:therapeutic use; D008297:Male; D008875:Middle Aged; D009043:Motor Activity / Q000502:physiology; D019518:Postprandial Period
chemical_list: D001786:Blood Glucose; D002096:C-Peptide; D007004:Hypoglycemic Agents; D007328:Insulin; D061267:Insulin Aspart