Diagnostic Tests for Diabetes
Don’t wait for symptoms to show up! Get yourself screened for diabetes at least once a year.
It is a fact that millions of people are living with undiagnosed diabetes and are unaware of their condition. It is only after they feel acute symptoms of diabetes that they consult a doctor and get laboratory tests done.
The onset of type 2 diabetes is generally slow and it takes some time for many to feel the symptoms, but type 1 diabetes is sudden in onset and people start feeling the symptoms in a few weeks. So for them, the screening process begins early on and appropriate treatment is prescribed.
However, in the case of type 2 diabetes, it is advised that people above 30 years of age get themselves screened once a year. This is because India has more than 69.1 million people with diabetes and the age of incidence is decreasing every year.
Screening for Diabetes
People who have a family history of diabetes, are overweight, and who lead a sedentary lifestyle are at risk of getting diabetes. Moreover, people who have high blood pressure, high cholesterol levels, vascular diseases, and women with PCOS are also at risk. It is for this reason that such people need periodical screening tests for diabetes.
Screening tests done for diabetes:
- Random blood glucose test.
- Fasting plasma glucose test.
- Oral Glucose tolerance test (OGTT).
Diagnostic Tests done for Diabetes
Diagnosing the presence of glucose in the bloodstream, the presence of proteins in the urine and conducting investigations for complications of diabetes is an important aspect of condition management. Periodical diagnostic tests allow the healthcare providers to improve treatment plans and motivates the patients to adhere to the treatment.
Diagnostic tests done for type 1 diabetes
Random blood glucose test.
Fasting plasma glucose test.
HbA1c (glycated hemoglobin) test.
Oral glucose tolerance test.
GAD autoantibodies test.
C-peptide, insulin.
Blood or urine ketone test.
Diabetes autoantibodies are tested to distinguish between type 1 and type 2 diabetes and blood/urine ketone test is done to determine hyperglycemia and ketoacidosis.A C-peptide test is done to detect the amount of insulin produced by the pancreas and to distinguish between type 1 and type 2 diabetes.
Diagnostic tests done for type 2 diabetes
Random blood glucose test.
Fasting plasma glucose test.
Postprandial glucose test.
HbA1c (glycated hemoglobin) test.
Oral glucose tolerance test.
Additional tests like urine tests to determine microalbuminuria and eye tests like fundoscopy are done to determine the damage to the kidneys and eyes due to diabetes.
It is also important for people with diabetes to get periodical lipid profile tests in order to determine the total cholesterol levels in the body as cardiovascular disease is a major comorbidity for people with diabetes.
Some diabetics might need examinations of their feet by a podiatrist in order to determine foot damage due to diabetic neuropathy. Tests like vibration perception threshold test, and testing the sweat glands of the feet are done.
Random blood glucose test:
A random blood glucose test is done to determine the amount of glucose in the bloodstream. This test is done irrespective of whether the patient is on a fast or not. This test can be done either with the help of a glucometer or by drawing venous blood from the arm.
Random Blood Glucose Test and Condition Management
Random glucose test allows healthcare professionals to detect the presence of hyperglycemia. This test is effective in the management of diabetes as glucose levels vary with diet, activity, and stress levels.
Keeping a track of the random blood glucose levels allows the healthcare team to have better insights and thereby provide more accurate treatment plans. By measuring and recording blood glucose levels periodically, the patient is also motivated to gain control over diabetes.
Patients can also measure random blood glucose levels as and when they experience any symptoms of low or high sugar levels. This allows them to take immediate action. Random blood glucose test also helps patients avoid low blood sugar levels, especially after physical activity.
Random blood glucose test is an important aspect of insulin management as patients can adjust the levels of insulin with respect to the glucose levels; however, this has to be done only after the patient receives initiation through a Diabetes Self-Management Program or insulin training.
Random blood glucose test results:
| Random Blood Glucose level (mg/dl) | Findings |
| 79mg/dl to 140 mg/dl | Normal |
| 140mg/dl to 200 mg/dl | Prediabetes |
| Above 200 mg/dl | Diabetes |
Fasting plasma glucose test:
This test enables doctors to determine the presence of both prediabetes and diabetes. This test is generally done in the morning after fasting for 8 to 10 hours without drinking or eating anything (except water). This test is done by taking a blood sample from the arm of the patient.
Depending upon the results of the test, further investigations are considered by doctors.
| Blood Glucose Level (mg/dl) | Findings |
| Below 110 mg/dl | Normal |
| Between 111 to 125 mg/dl | Impaired fasting glucose (Prediabetes) |
| 126mg/dl and above | Diabetic |
Postprandial Glucose Test:
A postprandial glucose test is done two hours after consuming food. This test determines the amount of glucose in the bloodstream after food. After consuming food, it is natural for a person to have increased blood glucose levels. However, as soon as a person consumes food, the pancreas releases insulin and this helps in the glucose being absorbed in the cells.
When a blood glucose test is done two hours after the consumption of food, the blood glucose levels should show a drop as insulin should have assisted the absorption of glucose. Since this does not happen well in people with diabetes, the levels of blood glucose after food determines the diabetes control of a patient.
The results assist a healthcare practitioner to determine the efficacy of the treatment, and evaluate the presence of low/high blood sugar levels.
The test can be performed with the help of a glucometer or by drawing venous blood from the arm of the patient.
Postprandial glucose test results:
| Postprandial glucose levels (mg/dl) | Findings |
| Below 140 mg/dl | Normal |
| Between 140 to 199 mg/dl | Prediabetes |
| 200 mg/dl and above | Diabetic |
| More than 190 mg/dl (after one hour) | Gestational Diabetes |
Oral Glucose Tolerance Test (OGTT):
This is yet another test referred by doctors to diagnose prediabetes, diabetes, and gestational diabetes and is a better indicator of diabetes than a finger prick test. This test determines the efficiency of carbohydrate metabolism of the body and a lack of it indicates diabetes.
A patient is asked to fast for a time period of 8 to 12 hours without consuming any food or fluids. Depending upon individual conditions, doctors may recommend avoiding certain medications.
First, the glucose level in the blood is measured with the help of a blood sample. The patient is then given a sweet glucose drink. In time intervals of 30 minutes, 60 minutes, and 2 hours further blood samples are collected and the blood glucose levels are measured.
| Blood Glucose Levels (mg/dl) after two hours | Findings |
| Less than 140 mg/dl | Normal |
| Between 140 to 199 mg/dl | Impaired Glucose Tolerance (Prediabetes) |
| 200 mg/dl and above | Diabetic |
| More than 190 mg/dl (after one hour) | Gestational Diabetes |
HbA1c (Glycated Hemoglobin):
Importance of HbA1c:
Glycated hemoglobin (HbA1c) is a major diagnostic test done to determine the control a patient has over diabetes. It is the objective measure used to evaluate glycemic control. A higher HbA1c indicates a poor control and a lower value indicates better control.
A higher amount of HbA1c increases the number of free radicals in the blood cells. Free radicals are major contributors to cell damage in the body. That is why poor control of diabetes leads to numerous complications including nephropathy, retinopathy, neuropathy, and cardiovascular diseases.
Added to that, the buildup of free radicals leads to improper vasodilation (expansion of blood vessels) increasing the blood pressure. It also causes improper plaque-inhibition mechanisms leading to the buildup of LDL (bad cholesterol) causing cardiovascular diseases.
How is HbA1c test done?
HbA1c is the measure of the average plasma glucose concentration over a period of 8 to 12 weeks. Since it measures the average plasma glucose concentration over a period of time instead of a value in a single point in time, it is a better diagnostic test than other tests. This test is done every three months and it measures the exposure of the red blood cells to plasma glucose.
HbA1c test has to be done in a diagnostic center and requires no fasting.
Venous blood is drawn from the arm and the samples are sent to a laboratory for evaluation. HbA1c test results are accurate indicators of diabetes control except in cases of iron deficiency, anemia, and recent blood transfusion. Results can also be inaccurate with the presence of kidney damage or the intake of certain vitamin supplements like vitamin E and C.
Doctors prescribe both blood glucose tests and HbA1c for a comparison. Depending upon the fluctuations of blood glucose levels and the HbA1c levels, treatment plans are improved upon.
Treatment plans concentrate on reaching the target HbA1c levels. These targets are determined by the patient’s condition and the discretion of the healthcare providers.
HbA1c Results
| HbA1c levels (%) | Findings |
| Below 6% | Normal |
| Between 6.0% to 6.4% | Prediabetes |
| 6.5% and above | Diabetes |
