Can insulin make obese patients unresponsive to antihypertensive drugs?

It is unlikely that the insulin itself is making her respond poorly to the antihypertensive medications. Both hypertension and diabetes can detrimentally impact the other condition. Therefore, having good control over her sugar should help improve control over her hypertension (and vice versa). Using a device to monitor her blood pressure regularly is helpful in determining if the hypetensive medication is effective or not. A healthy diet and exercise is further helpful in managing this condition.