The use of combination drugs of different mechanism of action at a lower dose to control diabetes better is a common practice for a lot of GP.
Amaryl (glimepiride) works by increasing the release of pre-formed
insulin from the pancreas.
Metformin works by increasing the peripheral insulin sensitivity and reducing glucose production in liver.
Lipitor is a HMG coA-reductase inhibitor (ACEI) to inhibit production of cholesterol in liver.
Lisinopril is a angiotensin converting enzyme inhibitor to reduce production of angiotensin 2 and hence inhibit BP rise.
For diabetic patient, it is essential to control the BP below 130/80 and lipid profile should be carefully controlled to prevent cardiovascular events.
ACEI, according to a lot of clinical stuides, has been shown to improve CV outcomes in diabetic patients.
You mentioned that eposide of hypoglycemia (low blood sugar level) was experienced, it's probably due to the drug amaryl because it can cause drug-induced hypoglycemia. But it is also possible that combination drugs work together to bring the sugar to a excessively low level.
You may consider changing the dose or changing the drug after discussing with your physician.
Lisinopril is associated with impotence as a side effect, but not other drugs u have listed. However, it should be emphasized that autonomic neuropathy, which is a complication of diabetes, also produce symptoms e.g. impotence, postural hypotension.
Therefore, you'd better check with the doctor to see it is a sign of aggravation or a drug-induced side effect.
Viagra should not be used with a few high BP med, namely alpha blocker and organic nitrates, but not with all high BP med.
The reason why viagra decreases in action in your husband's case may be due to the side effect of lisinopril. But as long as the hypertension is well controlled, the use of viagra shall be alright.
Sorry that I have include such a lot of info here as I hope you may find some info useful.