This study is an open label, prospective, randomised comparative, single center study. In the present study, the impact of a 12-week pulsatile insulin infusion therapy (PIT) with Humulin R 100 from

During the screening visit the patient will arrive at the study site and written informed consent will be obtained. Inclusion and exclusion criteria will be controlled and blood will be drawn for HbA1c and safety parameters. A point of care treatment (POCT) pregnancy test will be conducted in women of childbearing age. Patient demographics and history will be collected and a physical examination will be performed. The patient will complete a QoL, the continous glucose monitoring (CGM) sensor will be placed and trained, and the schedules for the subsequent treatment visits will be made. Also, the randomization (2 h vs 3 h) will be performed.

During the initiation visit , a series of clinical assessments will be made to document the patient status with respect to secondary complications: sensory nerve perception thresholds (tuning fork and path tester), retinopathy (RetinaVue camera). An ECG will be conducted, and blood will be drawn for assessment of the efficacy parameters. Thereafter the pulsatile insulin infusion therapy (PIT) procedure will be initiated.

For each PIT procedure: a venous catheter will be placed into one superficial vein at one arm, which will be connected to the insulin infusion pump and a glucose infusion pump via a three-way connector. Endothelial function will be measured by means of the Vendys 2 device (manufacturer: endothelix). The blood glucose will be tested by means of a POCT meter and the CGM, and the PIT procedure will be started (10 pulses of 3 U of regular human insulin per hour). Blood glucose will be tested every 5 to 10 min and glucose infusion will be started once a drop in blood glucose is detected. Adjustment of glucose administration will be performed until a stable glucose value between 80 mg/dL to 160 mg/dL is reached. In parallel, endothelial function will be measured every 30 min. At the end of the PIT procedure, the venous catheter will be removed and the patient will be discharged until the next visit.

During all consecutive treatment visits the patient will arrive at the investigational site at the agreed time-point and information regarding potential adverse events will be collected. Vital signs will be measured and the PIT procedure will be performed as described. At visits V6 and V10 additional examinations (assessments of neuropathy and retinopathy, blood draws for efficacy parameters, diabetes treatment satifaction questionnaire (DTSQ) questionnaire) will be performed.

During the final Visit the assessments from baseline (ECG, physical examination, neuropathy assessments, retinopathy assessment, blood draws for all safety and efficacy parameters incl. messenger ribonucleic acid (mRNA) analysis) will be repeated. The patient will complete a final DTSQ questionnaire, which concludes the participation in the trial.

Inclusion Criteria:

1. Informed consent obtained prior to any trial-related activities
2. Male or female > 18 years
3. Diagnosed with Type 1 or 2 Diabetes ≥ 2 years
4. HbA1c <10%
5. Nephropathy with GFR between 30 and 60 mL/min/1,73m2 or < 75 GFR together with proteinuria and/or elevated creatinine levels
6. Patient is naïve to pulsatile insulin treatment

Exclusion Criteria:

1. Patients participating in another investigational drug study
2. Current or history of dialysis therapy
3. Anemia with hemoglobin < 10 g/dL
4. Unstable significant cardiovascular disease with admission to emergency room or hospital in last 45 days
5. Patients with diagnosed renal failure from non-diabetic etiology
6. Pregnancy or breast feeding
7. Patient unwillingness to use a CGM device, or inability (with or without family assistance) to replace the sensor every two weeks on the study CGM device
8. Drug or alcohol abuse
9. Sexually active woman of childbearing age not practicing birth control by accepted methods
10. Lack of compliance or other reason that in the discretion of the investigator precludes satisfactory participation in the study
11. Any severe illness preventing participation in the study per protocol (in the discretion of the investigator)