BP of 43? Anything below 90/60mm is bad. If he is experiencing dizziness, fatigue, or nausea it could be a sign of serious underlying conditions such as a heart condition, blood infection or damage to the nervous system [flickering eyes].
You kept it a secret as to what country you reside in. This is important to know as the two most common glucose test results are identified as mg/dl [American] and mmol/l [European] and differ in meaning from each other. As such, we cannot tell if the glucose level of 16 was prandial [before a meal] or postprandia] [after a meal] so I'll present both sides as prandial.
Glucose of 16 mg/dl: This is dangerously low as it could put your husband into coma.
Glucose of 16 mmol/l: This is getting high and could put your husband into cardiac arrest if left untreated.
As you can see the mg/dl number is life threatening where the mmol/l is considered out of control glucose management - his medication needs adjustment. In either case your husband needs to see a doctor ASAP for an thorough evaluation.
I believe a blood sugar of 16 is an emergency--did his doctor provide him with quick disolving glucose tablets or some other advice in dealing with very low sugar levels? The flickering vision should also be checked out. If these conditions persist you may want to think of calling 911 or taking him to the emergency room.
Please let us know how your husband is doing over the next day or so.
Troytroy