PT  - JOURNAL ARTICLE
AU  - Hao, Wei
AU  - Greenbaum, Carla J.
AU  - Krischer, Jeffrey P.
AU  - Cuthbertson, David
AU  - Marks, Jennifer B.
AU  - Palmer, Jerry P.
TI  - The Effect of DPT-1 Intravenous Insulin Infusion and Daily Subcutaneous Insulin on Endogenous Insulin Secretion and Postprandial Glucose Tolerance
AID  - 10.2337/dc14-1825
DP  - 2015 May 01
TA  - Diabetes Care
PG  - 891--896
VI  - 38
IP  - 5
4099  - http://care.diabetesjournals.org/content/38/5/891.short
4100  - http://care.diabetesjournals.org/content/38/5/891.full
SO  - Diabetes Care2015 May 01; 38
AB  - OBJECTIVE To investigate the effect of parenteral insulin therapy on endogenous insulin secretion in the Diabetes Prevention Trial–Type 1 (DPT-1).RESEARCH DESIGN AND METHODS In the parenteral insulin arm of DPT-1, subjects without diabetes at high risk of future type 1 diabetes randomized to active treatment received a yearly 4-day intravenous insulin infusion (IV-I) and daily subcutaneous insulin (SC-I). To examine the effects of these insulin therapies on endogenous insulin secretion, C-peptide and glucose levels were compared during oral glucose tolerance tests (OGTTs) performed on and off IV-I and SC-I. Forty-six paired OGTTs were performed in 30 subjects from DPT-1 to determine the effect of IV-I. Twenty paired OGTTs were performed in 15 subjects from DPT-1 to determine the effect of SC-I.RESULTS IV-I suppressed fasting and OGTT-stimulated C-peptide (62% and 40%, respectively), and it significantly lowered fasting glucose (67.4 ± 4.5 mg/dL during IV-I vs. 90.9 ± 1.8 mg/dL off insulin; P < 0.05). By contrast, post-OGTT glucose levels were significantly higher during IV-I: Glucose during IV-I versus off insulin at 120 min was 203.9 ± 15.1 vs. 151.6 ± 10.2 mg/dL, respectively (P < 0.05); 49% of OGTTs became transiently diabetic (>200 mg/dL at 120 min) when receiving IV-I. Fasting glucose was significantly lower when receiving SC-I versus when off insulin (85 ± 3 vs. 94 ± 2 mg/dL, respectively; P < 0.05), but SC-I did not significantly alter fasting or OGTT-stimulated C-peptide compared with being off insulin.CONCLUSIONS These data demonstrate that the IV-I used in the DPT-1 markedly suppressed endogenous insulin secretion, which was frequently associated with postprandial glucose intolerance. SC-I, however, did not.