It was once commonly used during PCT in the belief it will aid testosterone restoration, however this is flawed due to its mechanism of action. The drug mimics the effects of LH in the body, stimulating the Leydig cells to produce testosterone in the testes . This can be fruitful in rectify existing, or avoiding testicular atrophy on cycle. It will not aid the process of recovery in the post cycle phase however, as the drug will bring about heightened oestrogen levels due to the greater aromatising of the testosterone being produced in the testes , thus bringing about greater inhibition of the HPTA .
Taking any form of Steroid if you are diabetic is never a good thing as it makes controlling diabetes B/G levels very much harder due to the inevitable rise in B/G levels. Steroids causes an impact in the body basal metabolism, which makes diabetic patients a susceptible target to that impact increasing or moving the lipid profile and glucose levels to the roof is not regularly control and checked. The short term complications can vary and be very simple(or not) long term complications are a big problem here (macro and micro-vascular complications). Can you use them? maybe… but at the end is your decision. Never do anything without consulting your physician.