Ravi Retnakaran1,2,3, Alexandra Emery1, Chang Ye1, Stewart B Harris4, Sonja M Reichert4, Natalia McInnes5, Hertzel C Gerstein5, Kevin E Thorpe6,7, Caroline K Kramer1,2,3, Bernard Zinman1,2,3. 1. Leadership Sinai Centre for Diabetes, Mount Sinai Hospital, Toronto, Ontario, Canada. 2. Division of Endocrinology, University of Toronto, Toronto, Ontario, Canada. 3. Lunenfeld-Tanenbaum Research Institute, Mount Sinai Hospital, Toronto, Ontario, Canada. 4. Department of Family Medicine, Schulich School of Medicine and Dentistry, Western University, London, Ontario, Canada. 5. Division of Endocrinology, McMaster University, Hamilton, Ontario, Canada. 6. Applied Health Research Centre, Li Ka Shing Knowledge Institute, St. Michael's Hospital, Toronto, Ontario, Canada. 7. Dalla Lana School of Public Health, University of Toronto, Toronto, Ontario, Canada.
Abstract
AIM: To test the hypothesis that the addition of periodic courses of short-term intensive insulin therapy (IIT) could enhance the effect of metformin (MET) maintenance therapy on preservation of beta-cell function following induction IIT. METHODS: In this multicentre, randomized controlled trial, 108 adults with type 2 diabetes (median 1.3 years' duration; HbA1c 6.6% ± 0.6%) were randomized to 3 weeks of induction IIT (glargine, lispro) followed by MET maintenance, either with or without periodic 2-week courses of IIT every 3 months for 2 years. Beta-cell function was assessed by the Insulin Secretion Sensitivity Index-2 (ISSI-2) at an oral glucose tolerance test every 3 months. RESULTS: In both arms, induction IIT increased ISSI-2, improved whole-body insulin sensitivity and reduced hepatic insulin resistance (all P ≤ .0004). The primary outcome of baseline-adjusted ISSI-2 at 2 years was not improved by the addition of intermittent IIT (MET + IIT) and was slightly higher in the MET arm (baseline-adjusted difference -35 [95% CI: -66, -3]), with three additional beta-cell measures showing no significant differences. Baseline-adjusted HbA1c at 2 years did not differ between MET and MET + IIT (6.3% ± 0.1% vs. 6.4% ± 0.1%, P = .46), with 32.6% of participants in each arm maintaining HbA1c of 6.0% or less at 2 years. CONCLUSION: Although initial induction IIT induces metabolic improvement, subsequent repeat courses of IIT every 3 months do not further enhance the effect of MET maintenance therapy on beta-cell function.
RCT Entities:
AIM: To test the hypothesis that the addition of periodic courses of short-term intensive insulin therapy (IIT) could enhance the effect of metformin (MET) maintenance therapy on preservation of beta-cell function following induction IIT. METHODS: In this multicentre, randomized controlled trial, 108 adults with type 2 diabetes (median 1.3 years' duration; HbA1c 6.6% ± 0.6%) were randomized to 3 weeks of induction IIT (glargine, lispro) followed by MET maintenance, either with or without periodic 2-week courses of IIT every 3 months for 2 years. Beta-cell function was assessed by the Insulin Secretion Sensitivity Index-2 (ISSI-2) at an oral glucose tolerance test every 3 months. RESULTS: In both arms, induction IIT increased ISSI-2, improved whole-body insulin sensitivity and reduced hepatic insulin resistance (all P ≤ .0004). The primary outcome of baseline-adjusted ISSI-2 at 2 years was not improved by the addition of intermittent IIT (MET + IIT) and was slightly higher in the MET arm (baseline-adjusted difference -35 [95% CI: -66, -3]), with three additional beta-cell measures showing no significant differences. Baseline-adjusted HbA1c at 2 years did not differ between MET and MET + IIT (6.3% ± 0.1% vs. 6.4% ± 0.1%, P = .46), with 32.6% of participants in each arm maintaining HbA1c of 6.0% or less at 2 years. CONCLUSION: Although initial induction IIT induces metabolic improvement, subsequent repeat courses of IIT every 3 months do not further enhance the effect of MET maintenance therapy on beta-cell function.