A study population with impaired fasting glucose levels, impaired glucose tolerance levels and diabetes (with or without complications) along with healthy patients will be chosen as participants. Their vital signs and their ECG (electrocardiograph) will be recorded during their only visit. Data analysis will be performed using the vital signs parameters. The RR intervals from the ECG will be analyzed by 5 different techniques to determine the best technique that stratifies the subjects the most accurately.

The Autonomic Nervous System (ANS) is a fundamental part of the nervous system in the body. And yet, there is no technique to test or measure the health and functioning of a person's autonomic nervous system.This type of study will determine the most accurate methodology to test the autonomic nervous system through heart rate variability (HRV) monitoring and gain vital information to distinguish patient groups in the diabetic population.

There is no gold standard for measuring autonomic dysfunction. Currently the method of power spectral analysis is finding very wide usage. It Is known that power spectral analysis does not discriminate the two subsystems of the ANS well. There are other beat to beat methodologies that have not yet gained traction. The reason for conducting this trial is to take a group of subjects in various stages of impaired fasting glucose, impaired glucose tolerance and diabetes (with and without complications) and determine which methodology stratifies these subjects most accurately.

Our study aims to introduce a new measurement method named the 'Beat to Beat' (BB) method for gauging autonomic dysfunction in patients. The investigators hope to observe that the average beat to beat method (BB) score could help discriminating diabetic patients into the following five distinct groups from the pilot study:

1. Normal Glucose Tolerance (NGT) is defined as a plasma glucose concentration i.e < 140 mg/dl.
2. Impaired Fasting Glucose (IFG) is defined by an elevated fasting plasma glucose (FPG) concentration i.e ≥ 100 and < 126 mg/dl.
3. Impaired Glucose Tolerance (IGT) is defined by an elevated post-prandial plasma glucose concentration i.e ≥140 and < 200 mg/dl.
4. Presence of confirmed diabetes (HbA1c level > 6.4 %) without complications i.e no neuropathy, no retinopathy, no nephropathy etc.
5. Presence of confirmed diabetes (HbA1c level > 6.4 %) with at least one of the above complications.

By showing that this measurement bears no relationship to the other four vital signs parameters (heart rate, blood oxygenation, blood pressure, body temperature), it will prove the necessity of this measurement in addition to the four vital signs for distinguishing patient groups among the diabetic population.

Inclusion Criteria:

1. Able to provide informed consent
2. Age between 18 to 85
3. Body Mass Index (BMI) between 25 and 40 kg/m2
4. Individuals with normal glucose levels, pre-diabetes and diabetes Type 2 for at least 1 year (diagnosed by ADA criteria) and up to 20 years
5. Stable dose of meds for 3 months
6. Stable diet and lifestyle for 3 months
7. Medical history without clinically significant abnormalities

Exclusion Criteria:

1. Have a disorder that would impede performing the HRV measurement procedure (i.e., abnormal cardiac rhythm, heart disease, including coronary artery disease, angina, and arrhythmia, cardiac pacemaker, stroke, panic attack, cognitive impairment, renal failure)
2. Chronic disease (e.g. HIV, Cushing syndrome, CKD, acromegaly, active hyperthyroidism etc.)
3. Cancer and anticancer treatment in the last 5 years
4. Pregnancy or lactation
5. Subjects with major physical disability
6. Subjects with previous history of cerebrovascular accident
7. Any disorder, which in the investigator's opinion might jeo

Adults of either sex with various stages of impaired fasting glucose tolerance levels and diabetes (with or without complications) will be considered as study population.