Changes in the concentration of serum C-peptide in type 2 diabetes during long-term continuous subcutaneous insulin infusion therapy Department of Internal Medicine 1 and Biochemistry 2 Konkuk University and School of Medicine, Seoul , South Korea Soo-Bong Choi 1, Jun-Ho Lee 2, Jin-Hee Park 2, Yun-Hee Noh 2

Adapted from UK Prospective Diabetes Study (UKPDS) Group. Lancet. 1998;352: , with permission. UKPDS Progression of Hemoglobin A1c

Effects of intensive insulin therapy on  –cell function in type 2 diabetes 1. Induction of long-term normoglycemia without medication in Korean type 2 diabetes patients after continuous subcutaneous insulin infusion therapy. (Diabetes Metab Res Rev 19,24,2003) 2. Short-term intensive insulin therapy in newly diagnosed type 2 diabetes. (Diabetes Care 27,1028,2004) 3. Induction of long-term glycemic control in newly diagnosed type 2 diabetic patients is associated with improvement of b–cell function. (Diabetes Care 27,2597,2004) 4. Effect of intensive insulin therapy on b–cell function and glycemic control in patients with newly diagnosed type 2 diabetes: a multicentre randomised parallel-group trial. (Lancet 371,1753,2008)

Holman RR. Diabetes Res Clin Pract 1998,40 (Suppl),S21 β -cell function(%) Previous concept: Progressive loss of β-cell function over time in T2DM Recently emerging concept: Restoration of impaired β-cell function in newly diagnosed T2DM AIM OF THE STUDY To see if β-cell function is improved in patients with type 2 diabetes at any time point of the disease via long-term CSII. ?

Konkuk University Cohort Improvement of cardiovascular risk factors in patients with type 2 diabetes after long-term continuous subcutaneous insulin infusion. (Diabetes Metab Res Rev 24,384,2008) Induction of long-term normoglycemia without medication in Korean type 2 diabetes patients after continuous subcutaneous insulin infusion therapy. (Diabetes Metab Res Rev 19,24,2003) Started in 1979 To achieve optimal glucose control in T2DM using CSII Newly and previously diagnosed Publications ; Insulin requirement profiles of patients with type 2 diabetes after achieving stabilized glycemic control with short-term continuous subcutaneous insulin infusion. (Diabetes Technol Ther 12,271,2010)

Type 2 diabetic patients: 217 subjects Diabetes Center at Konkuk University Hospital (September 2004-September 2010) Exclusion criteria : Serum creatinine > 1.5 mg/dl Cardiovascular or cerebrovascular complications Diabetic foot Any acute illness SUBJECTS and METHODS

217 Korean patients with type 2 diabetes (duration 11.4 ± 7.2 yrs) 217 Korean patients with type 2 diabetes (duration 11.4 ± 7.2 yrs) CSII 1-2 weeks of admission Short acting insulin analogues (insulin aspart or insulin lispro) Glycemic goal: / mg/dl measured 7 times by SMBG per day CONTINUATION of CSII for up to 60 Mo (median 30 Mo) Before & during CSII Therapy Standard formulated mixed meal (500 kcal; Carb 52.9, Fat 30.4, protein 16.7 kcal%) ingestion without applying insulin pump at least for 9 hours before the test Blood samplings: 0 and 2 h after ingestion of the standard test meal HbA1c C-peptide (fasting and 2 h after meal) Before & during CSII Therapy Standard formulated mixed meal (500 kcal; Carb 52.9, Fat 30.4, protein 16.7 kcal%) ingestion without applying insulin pump at least for 9 hours before the test Blood samplings: 0 and 2 h after ingestion of the standard test meal HbA1c C-peptide (fasting and 2 h after meal)

Baseline characteristics * P < 0.05, ** P <0.001 vs Male Baseline (Before CSII) AllMaleFemale N (54.8%)98 (45.2%) Age (yrs)58.9 ± ± ± 10.3 Duration of known diabetes (yrs)11.4 ± ± ± 7.3 Blood pressure (mmHg) Systolic (mmHg)130.1 ± ± ± 15.2 * Diastolic (mmHg)78.7 ± ± ± 9.8 BMI (kg/m 2 )24.56 ± ± ±3.55 Fasting plasma glucose (mg/dl)160.4 ± ± ± 67.1 Serum C-peptide Fasting (ng/ml)1.58 ± ± ± h After meal (ng/ml)4.50 ± ± ± 2.25 HbA1c (%)8.47 ± ± ± 1.86 Hemoglobin (g/dl)13.5 ± ± ± 1.2 ** Serum creatinine (mg/ml)1.03 ± ± ± 0.23 ** Free fatty acids (μmol/l)705.4 ± ± ± Total Cholesterol (mg/ml)170.7 ± ± ± 42.4 Triglyceride (mg/ml)124.8 ± ± ± 63.1 LDL cholesterol (mg/ml)103.1 ± ± ± 40.8 ** HDL cholesterol (mg/ml)44.4 ± ± ± 12.6 Previous treatment Diet only (%) OADs (%) Insulin (%) Combined (OADs + Insulin injection)

HbA 1c (%) Paired t-Test : * P < 0.01 vs Before CSII; a P < 0.01 vs 0.5 y ; b P < 0.01 vs 1 y; c P < 0.01, č P <0.05 vs 2 y ; d P < 0.01 vs 3 y * * * * * a a b ā b c a b č d b c d N(94) (117) (153) (63) (113) (207) (35) (%) (Years)

C-peptide (AC, ng/ml ) (202)(122) (158) (117) (37) (67) (97) N (ng/ml) (Years) * * * * * a a b a b c a b c d a č d e Paired t-Test : * P < 0.01 vs Before CSII; a P < 0.01 vs 0.5 y; b P < 0.01 vs 1 y; c P < 0.01, č P < 0.05 vs 2 y ; d P < 0.01 vs 3 y e P < 0.01 vs 4 y

C-peptide (PC 2h, ng/ml ) (179)(109) (135) (102) (28) (53) (86) N (ng/ml) (Years) * * * * * * a a b a b c ā b c d a b č d e Paired t-Test : * P < 0.01 vs Before CSII; a P < 0.01, ā P < 0.05 vs 0.5 y; b P < 0.01 vs 1 y; c P < 0.01, č P < 0.05 vs 2 y ; d P < 0.01 vs 3 y e P < 0.01 vs 4 y

Changes in TDD of insulin during CSII 64.1 ± 24.3 (U/day) 35.5 ± 23.5 * (U/day) * P < Initial CSII After CSII (41 ± 28 Months)

BMI (kg/m 2 ) Paired t-Test : * P < 0.01 vs Before CSII; ā P < 0.05 vs 0.5 y N(88) (110) (148) (66) (107) (166) (36) (Years) (kg/m 2 ) * * * * * ā

C-peptide (PC 2h, ng/ml) change by the mean HbA 1c subgroups during CSII a b (ng/ml) a ā Ъ a c c Unpaired t-Test: a P < 0.01, ā P < 0.05 vs ≤ 6.5; b P < 0.01, Ъ P < 0.05 vs 6.51 ∼ 7.59; c P < 0.01, č P < 0.05 vs ≤ 6.5 (81) (108) (28) (ng/ml) (%) P < P = 0.036P = Mean C-peptide (PC 2h) during CSII by the mean HbA 1c subgroups during CSII Mean HbA1c (%) ≤ 6.5 ≥

Duration (years) ≤ ∼ 9.9 ≥ 10 C-peptide (PC 2h, ng/ml) change by Disease Duration (at baseline) subgroups (Years) (ng/ml) a b ā a a a Mean C-peptide (PC 2h) during CSII by Disease Duration (at baseline) subgroups (Years) (29) (54) (134) (ng/ml) P = 0.009

BMI (kg/m 2 ) ≤ ∼ 24.9 ≥ 25 C-peptide (PC 2h, ng/ml) change by the mean BMI subgroups during CSII a ā ā ā (Years) (ng/ml) Mean C-peptide during CSII (PC 2h) by the mean BMI subgroups during CSII (kg/m 2 ) (73) (22) (118) (ng/ml) P = P = 0.012

Multiple linear regression analysis Dependent Variable: Mean C-peptide (PC 2h) during CSII therapy Correlation Analyses: Mean C-peptide (PC 2h) during CSII vs Mean HbA 1c during CSII, Disease duration at baseline, and Mean BMI during CSII therapy Beta P Age Mean HbA 1c during CSII Disease Duration at baseline Mean BMI during CSII0.261< r = P = Mean C-peptide PC 2h during CSII Mean A1C during CSII r = P = Duration of diabetesMean BMI during CSII r = P = Mean C-peptide PC 2h during CSII

Patients showing remission (N = 7) (%) (ng/ml) years 0 U/day* 44.3 ± 14.4 U/day * P < ± ± ± ± 2.43 Initial CSII After CSII (35.6 ± 20.7 Months) Before CSIIMean ± SDMinMax Age (years)50.6 ± Duration (years)5.5 ± BMI25.07 ± FPG (mg/dl)157.5 ± HbA 1c (%)8.4 ±

Summary 1.Long-term CSII therapy in patients with type 2 diabetes during up to 5 year-follow up Maintenance of euglycaemia Decrease in HbA 1c 8.43 ± 1.99  6.87 ± 0.73 % Continual Improvement of pancreatic β–cell function serum C-peptide levels (AC, PC 2hr) Reduction in the total daily dose of insulin by 45%

2. PC 2 h C-peptide level significantly associated with HbA1c, disease duration, and BMI 3. Remission of diabetes (N=7) Maintenance of HbA 1c below 6.5% Continual increase in PC 2 h C-peptide levels

CONCLUSIONS 1.The resolution of glucotoxicity and maintenance of euglycaemia through long-term CSII therapy may contribute to the continual restoration of β–cell function in terms of serum C-peptide levels in type 2 diabetic patients, not only at the onset, but at any time point of the disease. 2. The better restoration of β–cell function in terms of serum C-peptide levels during CSII therapy was associated with the shorter disease duration, the nearer normoglycmic HbA1c level, and the higher BMI level in Korean type 2 diabetes.