Diabetes can be called an iceberg disease, as there are many individuals with diabetes who do not know they have diabetes, because they do not have any diabetes symptoms. By the time diabetes becomes symptomatic it may take several years. So screening is an important tool for diagnosis of diabetes among asymptomatic individuals and for prevention of complications and morbidity due to diabetes. It is to note that approximately 50% of patients have some diabetes related complication at the time of diagnosis, especially in type-2 diabetes, hence screening is very important.

Testing of Fasting Plasma Glucose (FPG) for screening of diabetes is recommended, especially for type-2 diabetes, because (1) there are large number of people who meet the criteria for diagnosis of diabetes, but unaware that they have diabetes, as they are asymptomatic, (2) approximately 50% of individuals with type-2 diabetes have one or more diabetes complications at the time of diagnosis (3) epidemiologic studies have proved that type-2 diabetes may be present asymptomatically for up to a decade before diagnosis made and (4) appropriate management of type-2 diabetes can favorably alter the natural history of diabetes and become beneficial for the patient.

Who should be screened for diabetes?

American Diabetes Association recommends that all individuals above the age of 45 years of age should be screened every 3 years and individuals at an earlier age if they are overweight with BMI or Body Mass Index of more than 25 and have one additional risk factor for diabetes, which are given below:

· Family history of diabetes i.e., parent or sibling with type-2 diabetes

· Previous IFG or IGT

· Sedentary lifestyle, habitually

· Hypertension (blood pressure more than 140/90 mmHg)

· HDL (High Density Lipoprotein also called good cholesterol) cholesterol level below 35 mg/100 ml of blood (0.90 mmol/Liter) and/or a triglyceride level more than 250 mg/100 ml of blood (2.82 mmol/Liter)

· History of GDM (Gestational Diabetes Mellitus) or delivery of baby more than 4 kg (more than 9 lb)

· History of vascular disease, including cardiovascular disease

· Race/ethnicity (e.g. African American, Latino, Native American, Asian American, Pacific Islanders, as they have high prevalence of diabetes)

· Patients with polycystic ovary syndrome

· Patients with Acanthosis nigricans.

The screening is not recommended for type-1 diabetes as a long asymptomatic period of hyperglycemia is rare in type-1 diabetes before diagnosis. The initiation of appropriate management/precaution or preventive measures in type-1 diabetes does not have significant benefit, unlike type-2 diabetes and hence not recommended for screening.