DIABETES MELLITUS

The new guidelines issued by the American Diabetes Association changed the definition
of diabetes into Anyone with fasting glucose > 125 mg/dL on 2 separate occasions now
ualifies as diabetic (the old threshold was 140) – and any reading over 110 is considered impaired glucose tolerance.

MONITORING & FOLLOW UP OF DIABETIC PATIENTS :

Monthly Blood glucose + Fructosamine .
3 Monthly Glycosylated Hemoglobin + Microalbuminuria .
Yearly Liver & Kidney functions + Lipid profile .

GLYCOSYLATED HEMOGLOBIN (HBA1c) :

HBA1c is formed by addition of a glucose molecule to the beta chain of hemoglobin .
This process is formed progressively and irreversibly inside the red cells and is directly
dependent on the blood glucose concentration.
HBA1c is probably the best single measure for monitoring diabetes over a three month
period especially if the physician plans to alter or stop therapy.
However, this test does not give information about same day variations in blood glucose.
It can also be falsely low in anaemic patients and falsely high in patients with hemoglobinopathies.

FRUCTOSAMINE :

Fructosamine is formed by glucose linkage to albumin or other proteins.
It has the advantage over (HBA1C) of having a shorter half life hence is more
useful in monitoring diabetes over a one month period.
This test may give false results in patients showing plasma protein fluctuations
as in hemodialysis.

MICROALBUMINURIA

Microalbuminuria is the elevated excretion of urine albumin above the normal
amount and below that detected by conventional urinary protein tests.

REF. RANGES: Normal < 20mg albumin / gm creatinine.
Microalbuminuria 20-200 mg albumin /gm creatinine.
Persistent proteinuria > 200 mg albumin /gm creatinine.

APPLICATIONS :

1. Nephropathy whether due to diabetes or hypertension.
2. To monitor the efficacy of therapy in controlling diabetes or hypertension.
3. Microvasculature complications leading to nephropathy, retinopathy and neuropathy.
4. Complications affecting the macrovasculature and leading to coronory heart disease (CHD)
, cerebrovascular disease and peripheral arterial disease.

INSULIN & C-PEPTIDE :

Proinsulin is cleaved into Insulin and the biologically inactive C-peptide which are useful
parameters in the following conditions :
· True hypoglycemia & Insulinoma : both Insulin & C-peptide are elevated.
· Factitious hypoglycemia : Insulin is elevated & C-peptide is decreased .
· Residual B cell function in Insulin dependent diabetics: many of those patients have antibodies
that interfere with the Insulin assay; hence C-peptide is the parameter of choice .

INSULIN ANTIBODIES :

They develop from impurities in animal Insulin .
Presence of Insulin antibodies suggests one or more of the following ;
· Exogenous intake of animal Insulin .
· Insulin Autoimmune Hypoglycemia .
· Insulin resistance especially if associated with high titers >1:64 .

LIPID PROFILE:

Hyperlipidemia is suggested if
Total Cholesterol >200mg%
The risk of cardiac and vascular complications are increased if
HDL Cholesterol <35mg%
LDL Cholesterol >160mg%
All patients who perform these tests should be fasting for 12-14 hours.

PREDICTION OF DIABETES:

Testing can begin as early as 1-2 years of age and includes
1) Positive family history of diabetes.
2) HLA typing; More than 90% of (IDDM) patients are DR4-DQ8 or DR3-DQ2 or both.
3) Presence of more than one Autoantibody; Namely anti insulin,
ICA (islet cell antibody) or anti GAD (glutamic acid decarboxylase).