Hello,
Diuretics are routinely used to treat hypertension, even in high-risk individuals such as those with diabetes. In fact, nearly all ACE inhibitors or angiotensin receptor blockers use HCTZ in a fixed dose combination tablet. Having said this, diuretics can cause some adverse effects (e.g. elevated LDL, glucose, uric acid, volume contraction) but they can easily be monitored clinically and with blood tests. Most contemporary dosing of diuretics which is typically lower than what was used in the past, poses less risk for these adverse events. Nevertheless, there are other options besides diuretics; I have been increasingly using calcium channel blockers such as amlodipine in combination with ACE inhibitors like ramipril due to positive results from the ACCOMPLISH study.
Regarding your husband's renal function, I don't have enough information to comment completely. It would be important to know his urinary protein numbers and results of abdominal ultrasound to be able to answer more completely. If he lacks significant proteinuria or signs and symptoms of systemic disease that could lead to renal problems, the priority would be blood pressure control, and provided his function stabilizes, his physicians are correct to reassure you. I would avoid extrapolating too much from small, relatively short-term changes in kidney function to predict long-term outcomes.
Regards,
Dr. Jordan Weinstein