We investigated the effect of sequential treatment escalation with dapagliflozin and saxagliptin on beta cell function in patients with T2DM insufficiently controlled on metformin monotherapy during a hyperglycaemic clamp investigation. Twenty-six patients (19 males, age 63.5±7.0 years; duration of diabetes 8.8±4.7 years; HbA1c 63.9±15.8 mmol/mol; mean±SD) were enrolled in the study. During a first treatment period (TP1) all patients received 10 mg dapagliflozin for one month, followed by the addition of 5 mg saxagliptin or placebo for another month (TP2). At baseline and at the end of each treatment period, fasting glucose and insulin levels were analysed, and a hyperglycaemic clamp with the measurement of plasma C-peptide, insulin, proinsulin, and glucagon was performed. Treatment with dapagliflozin reduced fasting glucose levels and insulin resistance (TP1). Within the hyperglycaemic clamp, C-peptide and insulin concentrations increased after the addition of dapagliflozin in TP1 (0.48±0.45 nmol*h/l; 6.24±17.9 mU*h/l) and further improved after the addition of saxagliptin in TP2 (0.38±0.34 nmol*h/l; 6.59±10.15 mU*h/l). Acute insulin response did not change after the addition of dapagliflozin (TP1), but significantly improved after the addition of saxagliptin in TP2 (0.89±0.76 mU*h/l). Both drugs improved the C-peptide/proinsulin ratio. After the addition of saxagliptin, the glucagon/insulin ratio significantly declined (TP2). Treatment escalation with dapagliflozin and saxagliptin exhibit additive effects on beta cell capacity, and improves alpha and beta cell integrity.
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