Background: To evaluate the impact of switching from U-100 to U-500 insulin in patients with type 2 diabetes mellitus (T2DM) uncontrolled with continuous subcutaneous insulin infusion (CSII) by pump.
Methods: We retrospectively collected data from patients with T2DM, treated by U-100 CSII, who were switched to U-500 regular insulin where haemoglobin A1c (HbA1c) was >8% and/or insulin total daily dose (TDD) was >100 UI/d. Data collection from patient medical records included HbA1c, lipid levels, liver biomarkers, weight, TDD, declared hypoglycaemic episodes and measured by continuous glucose monitoring (CGM).
Results: Sixty-five patients were included, aged 63.9 ± 8.6 years, insulin pump since 3.7 ± 3 years, TDD 186 ± 52 U/day, body mass index 39.4 ± 5.3 kg/m², HbA1c 9.03 ± 1.6%. After switching to U-500 insulin, HbA1c dropped by -0.96% (P < 0.0001) at one year with the effect maintained at three years (- 0.95%, P < 0.01). A subgroup analysis (n=42/65) using a severity score which covered the three previous years on U-100 and the next three years on U-500 insulin confirmed the latter's efficacy. Body weight increased by + 4.8 kg and TDD by 16% at three years. Declared non-severe hypoglycaemia increased significantly three- to four-fold during follow up, but % time-below-range at six months did not differ between the two treatments. Baseline HbA1c correlated with improved glucose control with U-500.
Conclusions: U-100 to U-500 insulin switch improves glucose control in CSII T2DM patients, especially with high baseline HbA1c. Use of concentrated insulin in pumps may represent an advance in the strategy for treating T2DM insulin resistant states with uncontrolled hyperglycaemia after a switch from multiple daily injections to pump therapy.
Keywords: 500 U/ml regular insulin; Concentrated insulin; Continuous subcutaneous insulin infusion; Insulin resistance; Type 2 diabetes.
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