With the information that you have provided, it appears that diabetic gastroparesis is the main problem. However, I must say that in patients with bad diabetes and renal failure, if recurrent vomiting is a major problem, then one must exclude oral or oesophageal candida (fungal) infection. This can be best diagnosed by upper GI endoscopy. Endoscopy will also exclude other causes such as hiatus hernia, GE reflux, etc.
So you need to treat the underlying cause for vomiting. If gastroparesis is the only problem, then you should try Prokinetic agents such as Domperidone, Itopride, or erythromycin. Your doctor can advise you regarding this.