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DIAGNOSING DIABETES, PRE-DIABETES
AND
THE METABOLIC SYNDROME Indications for SCREENING
All those who complain of symptoms or show signs commonly associated
with diabetes must have a test for diabetes. Many people do not
manifest typical signs or symptoms commonly associated with T2DM
and therefore, if feasible, all persons over the age of 25 years
should undergo an annual test to rule out the presence of diabetes.
Persons at high risk MUST undergo testing when they present for
medical attention for whatever reason, and if negative, must have
a regular check, thereafter.
For a list of people who would be at high risk for T2DM, see Appendix
1a
It should always be remembered that
| A negative test for diabetes does NOT
mean that the person will never get diabetes. It only means
that the person does NOT have diabetes at the time of testing. |
In the occasional patient, especially
those manifesting characteristic signs and symptoms of diabetes,
one may be able to diagnose diabetes based on the result of a single
sample of blood.
In a patient with
characteristic sign and symptoms of diabetes, a fasting venous
plasma glucose >
126 mg%(7.0 mmol per L), OR, a random venous plasma glucose
> 200 mg% (11.1 mmol per L) , confirmed on repeat testing,
is diagnostic. negative test for diabetes does NOT mean that
the person will never get diabetes. It only means that the person
does NOT have diabetes at the time of testing. |
Urine examination for the presence of sugars should NEVER be
the method to diagnose diabetes.
The only presently accepted way of analysing blood for glucose is
to use to Glucose Oxidase method. It is also important to note whether
the laboratory, even though using the glucose oxidase method, uses
capillary blood, whole venous blood, or venous plasma for the estimation.
The levels of glucose in plasma are about 15% higher than the levels
in whole blood and the diagnostic criteria differ. Unless one is
aware of this, one will not be able to accurately interpret the
results.
Although the American Diabetes Association (ADA) feels that just
a fasting plasma glucose level should be adequate to diagnose diabetes,
the World Health Organization (WHO) has not given up the Glucose
Tolerance test (OGTT).
For a detailed note on the procedure
for carrying out an OGTT, see Appendix 1b
TABLE 1
| |
Glucose Concentration
mg/100ml (mmol/l) |
| |
Whole Blood |
Plasma |
| |
Venous |
Capillary |
Venous |
Capillary |
| Diabetes Mellitus |
| Fasting or |
>/=110 (6.1mmol/l) |
>/=110 (6.1mmol/l) |
>/=126 (7 mmol/l)
|
>/=126(7
mmol/l)
|
2 hours post Glucose Load
or both |
>/=180 (10.0mmol/l) |
>/=200 (11.1mmol/l) |
>/=200 (11.1mmol/l) |
>/=220 (12.2
mmol/l)
|
| Impaired Glucose
Tolerance |
| Fasting(If measured) |
<110 (<
6.1mmol/l)
|
<110 (< 6.1mmol/l)
|
<126 (<
7 mmol/l)
|
<126(< 7 mmol/l)
|
| 2 hours post Glucose Load |
>/=120 & <180(>/= 6.7 mmol/l
& < 10 mmol/l)
|
>/=140 & <200(>/= 7.8 mmol/l
& < 11.1 mmol/l)
|
>/=140 & <200(>/= 7.8 mmol/l
& < 11.1 mmol/l)
|
>/=160 &<220(>/= 8.9 mmol/l
& < 12.2 mmol/l)
|
| Impaired Fasting
Glycemia |
| Fasting |
>/=100 & <110(>/= 5.6 mmol/l
& < 6.1 mmol/l)
|
>/=100 & <110(>/= 5.6 mmol/l
& < 6.1 mmol/l)
|
>/=110 & <126(>/= 6.1 mmol/l
& <7.0 mmol/l)
|
>/=110 & <126(>/= 6.1 mmol/l
& <7.0 mmol/l)
|
| 2 hours PG (If measured) |
<120 (< 6.7 mmol/l)
|
<140 (< 7.8 mmol/l)
|
<140 (< 7.8 mmol/l)
|
<160 (< 8.9 mmol/l)
|
Many patients are diagnosed using blood
glucose meter readings especially in epidemiological surveys. Most
of the modern meters are callibrated to give the equivalent plasma
glucose readings. In the fasting state this does correlate with
the venous plasma glucose levels. But NOT in the non fasting state!
When used to evaluate the 2 hours postglucose results, it would
be better to use the capillary plasma glucose values for diagnostic
purposes.
The diagnosis of diabetes made by a using a meter should always
be confirmed by repeat testing on another day, preferably in a laboratory,
unless there is unequivocal hyperglycemia or obvious symptoms.
Most people tested would show “normal” values.
But,
"A NEGATIVE
TEST RESULT ONLY SHOWS THAT THE PERSON DOES NOT HAVE DIABETES
AT THE TIME OF TESTING. IT DOES NOT MEAN THAT THE PERSON WILL
NEVER GET DIABETES IN THE
FUTURE. WHICH IS WHY AN ANNUAL CHECKUP IS ESSENTIAL” |
Patients with IFG and/or IGT are now referred
to as having “pre-diabetes” indicating the relatively high risk
for future diabetes as well as cardiovascular disease. IFG and IGT
are associated with the metabolic syndrome, which includes obesity
(especially abdominal or visceral obesity), atherogenic dyslipidemia,
and hypertension. The presence of these metabolic disorders would
warrant specific treatment even if the patients are being monitored
for the future development of diabetes.
The metabolic syndrome is a cluster of risk factors which
predispose a person to Type 2 diabetes mellitus (T2DM) and atherosclerotic
cardiovascular disease (ASCVD). Its presence confers a two fold increase
in the risk for major CVD events and a five fold increase in the life
time risk for T2DM
The two most widely utilized diagnostic definitions are those of the
International Diabetes Federation (IDF) and the AHA/NHLBI (updated ATP-III). (Table 2)
Table 2
|
IDF
clinical criteria for metabolic syndrome
|
AHA/NHLBI
diagnostic criteria for metabolic syndrome
|
|
Measure
(central obesity sine qua non plus any two of four other criteria constitute a
diagnosis of metabolic syndrome)
|
Categorical
cut points
|
Measure
(any three of the five criteria below constitute a diagnosis
of metabolic syndrome)
|
Categorical
cut points
|
|
|
|
Central obesity
|
Waist circumference ethnic specific
( 80 cm for women) for Indian subjects
|
Elevated waist circumference
|
General U.S. population: 102 cm ( 40
in) in men, 88 cm ( 35 in) in women; lower cut points for
insulin-resistant individuals or ethnic groups (based on clinical
judgment)
|
|
Raised triglycerides
|
>150 mg/dl (1.7 mmol/l) or on specific
treatment for this lipid disorder
|
Elevated triglycerides
|
150 mg/dl (1.7 mmol/l) or on drug treatment for elevated triglycerides
|
|
Reduced HDL cholesterol
|
<40 mg/dl (1.0 mmol/l) in men, <50
mg/dl (1.3 mmol/l) in women or on specific treatment for reduced
HDL-C
|
Reduced HDL cholesterol
|
<40 mg/dl (1.0 mmol/l) in men, <50
mg/dl (1.3 mmol/l) in women
or on specific treatment for reduced
HDL-C
|
|
Raised blood pressure
|
< 130 mmHg systolic blood pressure
or 85 mmHg diastolic blood pressure or on treatment for previously
diagnosed hypertension
|
Elevated blood pressure
|
85 mmHg diastolic blood pressure or
on drug treatment for previously diagnosed hypertension
|
|
Elevated fasting plasma glucose
|
Fasting plasma glucose 100 mg/dl (5.6
mmol/l) or on treatment for previously diagnosed type 2 diabetes
|
Elevated fasting plasma glucose
|
100 mg/dl (5.6 mmol/l) or or on treatment
for previously diagnosed type 2 diabetes
|
Table 2. Diagnostic criteria for metabolic
syndrome from the International Diabetes Federation (IDF) definition
and the American Heart Association (AHA)/National Heart, Lung, and
Blood Institute (NHLBI) ( updated ATP-III) definition.
The IDF asks for an increase in central obesity as measured by the
waist measurement as a definite requirement for the diagnosis of
the metabolic syndrome. The NHLBI, although using waist measure
criteria which is focused on their population has also accepted
that people of different ethnic origins may require different individualized
waist measures.
The method to measure the waist circumference and Country/Ethnic
group specific diagnostic waist circumference measures in given
in Appendix 1c
Once a person has been diagnosed as having diabetes, they
need NEVER undergo a Glucose Tolerance Test. This test is only for
diagnosis.
To sum up,
Once a person is diagnosed to have diabetes,
he or she must be thoroughly investigated for the presence
of other components of the Metabolic Syndrome, such as hypertension,
lipid abnormalities, weight characteristics, especially central
obesity, presence of cardiovascular disease, novel risk factors
and for the presence of the long term diabetic complications.
As importantly, just because a person is not diagnosed
as having the Metabolic Syndrome, due to the absence of central
obesity or the absence of two of the other factors, does not
mean that the presence of any of the risk factor by itself should
NOT be treated! |
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