Imagine that despite not having eaten anything for almost 8 hours, your blood sugar can still be elevated! You may wonder, how is that possible? There are several mechanisms at play here. For a lay person, it is just important to remember that the carefully designed body has its own systems in place to adjust and maintain normalcy and prevent errors. It is only when we challenge the system beyond its capacity or ignore its basic needs that a problem arises!
Fasting blood samples are collected in the morning on an empty stomach. Water can be had before the test but no solid meals or beverages (tea/coffee, etc) are allowed. One needs to note the time of the dinner and ensure that they remain fasting for the next 8-10 hours. Fasting blood sugar levels >100 – <126 mg/dl indicate prediabetes or risk of diabetes and >126 mg/dl confirms diagnosis of diabetes. This test needs to be performed twice on separate days in order to get consistent results. However, this test alone is not used for confirmation of diabetes. Often it is used in conjunction with other tests such as postprandial sugar and HbA1c.
The hormones at play
We know that insulin is the hormone that helps to reduce hyperglycemia. High blood sugar signals the pancreas to release insulin which helps the glucose to enter different cells which need them.
Another hormone which is important to study here is glucagon. Whenever body detects low levels of glucose in blood, then glucagon is secreted which facilitates release of glucose from different storage forms. So in the fasting state, this hormone is active as blood glucose is apparently absent in blood during fasting. Glucagon causes an increase in the blood sugar by causing release of glucose from the cells.
In normal healthy individuals, this high glucose is brought down by getting absorbed into the cells guided by the action of insulin. However, in individuals with diabetes where insulin is either deficient or absent, the glucose is not absorbed into the cells. Hence in the fasting state also, the blood sugar levels of a diabetic individual tends to remain high.
Controlling glucose output by liver
Hepatic glucose output or release of the stored glucose from the liver is the major factor implicated in the management of fasting blood sugars. So there are two scenarios :
Dawn phenomenon: The hormones in our body cause an increase in blood sugar levels between 4am to 5am daily to prevent a major drop in blood sugar at night since the sugars from the last meal may get utilized by that time. This is a natural response in individuals with or without diabetes. In normal individuals, the insulin will regulate the increased blood sugar but in a diabetic, the blood sugar will continue to remain high. This is reflected as high fasting blood sugar.
Somogyi effect: This effect was named after Michael Somogyi, the researcher who first described it.In individuals with diabetes, usually some medication or insulin is given to manage the blood sugars that will rise after dinner. Once the glucose from the last meal gets utilized and slowly blood glucose levels begin to drop, the body enters a state of hypoglycemia. This nighttime hypoglycemia is common in individuals with diabetes and occurs around 3 am.
This drop in blood sugar is very dangerous for individuals with diabetes and needs to be monitored frequently .Often those on insulin experience this hypoglycemia in the form of sudden sweating or restlessness at around 3 am and sometimes may even faint. It can be fatal and hence needs to be checked!
The drop in blood sugars signal the pancreas to release glucagon which in turn causes release of glucose from the liver to compensate for low blood sugars. Hence, in the morning the blood sugar levels are elevated.
So, we can see that in both the cases, glucagon detects low blood glucose levels and compensates for the same by signalling the liver to release its stored glucose.
Treatment of fasting blood sugars
Check 3am sugar – Checking/ monitoring 3 am blood sugar is very important to understand whether there is a tendency for hypoglycemia at this time.
Include bedtime snack -A small snack just before going to bed can, in fact, lower fasting blood sugars. The logic behind it is simple- if you have eaten something closer to bedtime, then chances are that the sugar levels may not drop drastically around 3-4am . The type of food to recommended is a combination of protein and carbohydrates such as milk and nuts, boiled eggs, Apple with walnuts, fresh fruit yoghurt, etc . Proteins release glucose at a slower rate than carbohydrates and hence can prolong the drop in blood sugar at night.
Adjust medication/ insulin dose- For those on insulin therapy, taking an intermediate-acting insulin such as NPH or a long-acting true basal insulin such as insulin glargine at bedtime may help reduce chances of hypoglycemia at night.
Be active post dinner- Post-dinner activity such as walk or cleaning dishes etc can reduce fasting sugars. Any form of physical activity improves insulin sensitivity and this can help balance out the fluctuations in blood sugars
So whether the doctor emphasizes on maintaining normal fasting blood sugar levels or not, it is our responsibility to constantly monitor and maintain it. Effective management of fasting blood sugars have a profound effect on maintaining daytime blood sugars and development of the secondary complications of diabetes.