Successful switch from insulin therapy to treatment with pioglitazone in type 2 diabetes patients with residual β‐cell function: results from the PioSwitch Study

Aim: Insulin treatment is considered to be the final option for patients with progressive type 2 diabetes. This study investigated, whether reconverting type 2 patients from insulin treatment to oral treatment using pioglitazone is possible without deterioration of blood glucose control. Methods: The PioSwitch study was a prospective, open label, proof of concept study. Thiazolidinedione‐naïve patients with residual β‐cell function were switched from an existing insulin therapy to treatment with pioglitazone and glimepiride for 6 months. Efficacy was assessed by laboratory parameters and scores for evaluation of metabolic control, β‐cell function, insulin resistance and cardiovascular risk. Results: In total, 98 patients [66 men, 32 women, age (mean ± s.d.): 59 ± 9 years; disease duration: 5.6 ± 3.6 years; Hemoglobin A1c (HbA1c): 6.9 ± 0.8%; body mass index (BMI): 33.9 ± 5.2 kg/m 2 , initial daily insulin therapy dose: 0.36 ± 0.3 U/kg body weight] out of 117 screened patients were treated. During the observation period, 23 patients were prematurely terminated because of an increase in HbA1c from baseline > 0.5% or other reasons. In 75 patients (76%), no deterioration of glucose metabolism occurred and additional improvements were seen in the majority of the observation parameters [baseline vs. endpoint; HbA1c: 6.79 ± 0.74%/6.66 ± 0.69% (p < 0.05), glucose: 6.4 ± 1.5/5.2 ± 1.4 mmol/l (p < 0.001), adiponectin: 7 ± 3 mg/l/17 ± 8 mg/l (p < 0.001), C‐peptide: 987 ± 493/1756 ± 789 (p < 0.001), sensitivity index derived from the intravenous glucose tolerance test (SI(ivGTT)): 1.21 ± 0.85/1.49 ± 0.95 (p < 0.05), hsCRP: 3.3 ± 2.4/2.6 ± 2.4 mg/l (p < 0.01), macrophage chemo‐attractant protein 1 (MCP1): 487 ± 246/382 ± 295 ng/l (p < 0.05)]. BMI increased from 33.8 ± 5.1 to 34.4 ± 5.3 kg/m 2 (p < 0.001). Conclusions: The switch from insulin therapy resulting in a moderately HbA1c level, to oral treatment with pioglitazone was successful in a majority of patients with sufficient residual β‐cell function. It allows a simple and less expensive therapy with a better cardiovascular risk marker profile.