Blood sugar monitoring is indeed an important aspect of managing diabetes. Blood sugar monitoring has several advantages, mostly that it is cheap and accurate and can be performed by the patient, like your brother, at home. Testing involves a small portable machine that is purchased in any local pharmacy to which a small drop of blood is applied, obtained by pricking the fingertip.
Depending on what type of diabetes and how severe it is, your brother may be doing this several times a day. In particular, diabetics who need insulin injections in order to control their diabetes may be checking their blood sugar multiple times a day, such as before and after meals.
As you have mentioned, one of the dangers of diabetes management, especially when using insulin, is that it can cause the blood sugar to drop too low too fast. This can be quite dangerous and needs to be recognized immediately. If a diabetic feels some of the symptoms of low blood sugar, such as shaking, sweating, anxiety
, them will likely check their blood sugar using their machine right away. If the blood sugar reading is low they can usually correct this by eating or drinking a quick snack, such as orange juice.