How your blood sugar behaves upon eating depends upon factors such as the type, amount and composition of the food consumed. The blood sugar response after consuming food is called the post-meal or postprandial blood sugar and is usually recorded 2 hours after the meal is completed. This test is very vital in understanding the status of diabetes as high postprandial sugars give rise to complications such as diabetic retinopathy (eye problems), diabetic nephropathy (kidney problems), diabetic neuropathy (nervous disorders) and also brain stroke and heart disease.
Normal vs abnormal
In normal healthy individuals, the blood sugars will peak at 60 mins (at hour) and return to the fasting levels within 2 hours (120 min) after consuming meal. This peaking of blood sugar signals the pancreas to release insulin. Insulin helps in the absorption of glucose into the cells that require energy thereby causing clearance of glucose from blood.
The fasting levels are between 70-110 mg/dl and hence the post meal sugars are not expected to increase beyond 140 mg/dL. This indicates that it is time for the next meal as the sugars from the previous meal have been utilized. That is why there is an emphasis on eating every 2-3 hours but the meal needs to be small enough for all the sugars to be utilized and the composition of the meal also matters a great deal.
The return of postprandial sugars to near fasting levels is indicative of good metabolic health but in individuals who are obese or suffering from diabetes, the post meal sugar levels may not come down to 140 mg/dl by the end of 2 hours.
There could be 3 main physiological causes :
- No insulin: Insulin is not produced at all by the pancreas (Type 1 diabetes)
- Insulin insufficiency – Insulin is being produced in the body but it is not sufficient to bring down blood sugar (Type 2 diabetes)
- Insulin resistance – Insulin is produced in plenty but due to the metabolic derangements (fat deposition, etc) it is not properly recognized and functional at the cell surface (Obesity and related type 2 diabetes)
One can take the analogy of a gate-keeper at school – Insulin is like the gate-keeper who allows children (glucose) inside the school (body cells) knowing that classrooms are empty. The children fill-up the classrooms and then gate is closed. However, problem arises when –
- Gate-keeper is absent (No insulin) – Gates (cells) do not open and children (glucose) keep standing outside in large numbers.
- Gate-keeper is inefficient (insulin deficiency)- Gates are opened for only for short time not allowing all the children to go in.
- Gate-keeper has changed (Insulin resistance) – The new gate-keeper does not recognize the school children and hence does not allow them in.
In all of the above cases, glucose is not completely absorbed into the cells and keeps floating in the blood. This is called hyperglycemia or postprandial hyperglycemia. The consequences of this constantly high sugar in the blood is that cells which needed glucose did not get them so they are instructing the other tissues to release glucose. Glucose will then be removed from the reserves and released into blood. But in the absence of insulin, the glucose will not be able to enter cells and again more and more glucose will remain in circulation. Slowly this glucose starts to spill into the urine.
To depend or not to depend on insulin
However, we need to know some more interesting facts. The liver, muscle and fat (adipose tissue) cells need the insulin to bind to their surface for glucose to be absorbed but there are cells in the body that do not depend on insulin for glucose absorption. Cells in the brain, nervous system, heart, blood vessels and kidneys pick glucose directly from the blood freely and hence are more affected by the high supply of glucose.
So, if you remember, we mentioned earlier on that hyperglycemia impacts the eyes, kidney and nerves. It is because of the very fact that they do not need insulin gate-keepers so that excess glucose keeps flooding in and causes several problems such as failure to produce key enzymes, to repair themselves and to transport nutrients needed in the cells. This is further related to severe damage to their structure and function resulting in their gradual collapse. Too many children entering the school beyond its capacity to accommodate causing stampede and chaos. Also, too much sugar into the heart and brain cells leading to their dysfunction and collapse. Diabetes is not the cause for mortality, it is often the complications of diabetes that can kill.
Be your own Manager
Even though there are several tests to determine status of diabetes, postprandial sugars has its own significant value. If individuals with diabetes make it a point to record the post-meal sugar corresponding to the food intake, then management in terms of both diet and medication can become easy. If we know that oats upma leads to lesser increase in postprandial sugars as compared to plain suji upma then we become aware of the importance of fiber in managing blood sugars. This kind of observation / record maintained by the patient can also help the doctor to understand specific response of that person to that particular food/ food components. In fact, gradually we become independent and aware of our own response to foods and can regulate food intake accordingly.
Don’t get intimidated by diabetes,take charge of it!
Dr Pooja Chhawcharia is the Senior Nutritionist at eKincare with over 7 years of experience in Nutrition education, diet counseling and research. She is a Registered Dietician with the Indian Dietetic Association and Certified Diabetes Educator recognized by the International Diabetes federation . She is also interested in ancillary sciences such as Yoga and Naturopathy.