Hb A1c by Dr Sarma by cuiliqing

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									                     Paradigm shift in Diabetic care




                 Dr.R.V.S.N. Sarma, M.D., M.Sc.,
Dr.Sarma@works
                              How true ?
                 Once there was a tiger which boasted
                 that it can run faster than any one.
                 One day he chased a rabbit and failed to
                 catch it.
                 “All right” said the tiger; “of course I
                 failed on my boast.
                 But, remember the rabbit was running
                 for its life and I, for my dinner.”
                  Now, decide who is the rabbit and who
                 is the tiger - among we and our patient !
Dr.Sarma@works
                          Dr.E.P.Joslin
                 “The greatest burden on doctors will
                 be not the management of diabetes,
                 but the associated macro and micro-
                 vascular complications of it.” ..1926
                 “The goal of therapy in diabetes
                 should be to make serious efforts to
                 keep the blood sugar levels as close
                 normal as possible.” ….. 1929
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                         Be serious Doctor
                 1. I am making India the capital of the
                    world shortly !
                 2. Already I have a big… family of 200
                    millions on the globe.
                 3. I am happily troubling 12% urban and
                    8.2% of rural Indians.
                 4. In my name I am sweet but my
                    effects are very hot !
                 5. I am not easily controlled (< 45%)
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                            Haemoglobin
                 Structure of Hb




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                             Different Hbs

                 1.    Fetal Hemoglobin – Hb F
                 2.    Adult Hemoglobin – Hb A
                 3.    Sickle cell disease – Hb S
                 4.    Hemoglobinopathies – Hb C, Hb E

                      Glucose in the blood reacts with the
                      Hemoglobin A to form Glycated Hb.

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                      Glycated Hb - GHb
                 Different types of Glycation products
                 are formed from the HbA0 depending
                 on the carbohydrate moiety – namely
                 – HbA1a1 - Fr 1,6 diphos –N-term. valine
                 – HbA1a2 - Gl 6 phos –N-terminal valine
                 – HbA1b - Other CHO – N-term. valine
                 – HbA1c - Glucose –N-terminal valine
                  Normally less than 6% of Hb is HbA1c

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                      (Previously called glycosylated Hb.)
                 Reference values of HbA1c
                 1.   Less than 6% - Normal
                 2.   6 to 7.5% - Good control of DM
                 3.   7.6 to 9% - Unsatisfactory control
                 4.   More than 9% - Very poor control
                  Values depend on the method of estimation
                  They vary from lab to lab.
                  Note if all GHb is measured instead of HbA1c

Dr.Sarma@works
                 Factors affecting HbA1c
                 •   Acute hyperglycemia
                 •   Severe aneamia
                 •   Gestational diabetes
                 •   Life span of the RBC
                 •   Abnormal Hb like S-Hb, Hb C
                 •   Serum opalescence -↑TG
                 •   On the method of estimation
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                       Estimation of HbA1c
                 • There are many methods of estimation
                 • HPLC (High Performance Liquid
                   Chromatography) – Gold standard.
                 • Immuno-turbimetric meth. – HbA1cAb
                 • Affinity chromatography
                 • Electrophoretic methods
                 • Method based on chemical reactions.

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                 HbA1c is ‘weighted’




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                   How well it measures ?
                 Lowering Hb A1c reduces risk of complications




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                     Advantages of HbA1c
                 • Index of long-term control over 120
                   days and not a snap shot like PG
                 • Can be done at any time of day
                 • Not influenced by diet, exercise,
                   emotional disturbances on test day
                 • Useful index in clinical trials
                 • Useful if missed drugs / default diet
                 • Useful in DD of stress hyperglycemia
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                      Limitations of HbA1c
                 • Cannot be an emergency room test to
                   titrate Insulin or OHA dosage
                 • Cannot register hypoglycemia
                 • More sensitive to sin than repentance –
                   if it is elevated it confirms poor control,
                   if it is boarder line, it cannot assure
                   good control in the recent past.
                 • Not sensitive enough for use in GDM
                 •  Anaemia, Uraemia, Pregnancy
Dr.Sarma@works
                 Correlation of MPG - HbA1c
                        Mean Plasma Glucose =
                             (33.3 x HbA1C%) - 86
                   (Nathan et. al. NEJM, vol. 310, No 6, Feb 9, 1994)


                   HbA1C %                 Mean BG mg %

                         5                           80.5
                         7                          147.1
                         9                          213.7
                        11                          280.3
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                       Glycosylation of hair
                 •   Hair glycosylation using thiobarbituric acid TBA
                 •   Glycosylation of hair is  in diabetes mellitus
                 •   Both insulin dependent , non-insulin dependent
                 •   Glycosylation of hair is proportionate to HbA1c
                 •   Due to the presence of hexosyl lysome in hair
                 •   Long hair sample provides a long term record.
                 •   May have forensic application & in population
                     studies.


                                         BMJ, 1996, vol. 288 pp. 669-670
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                  Blood Glucose Monitoring
                     Type          Frequency        Sample

                  Type 2 DM         Monthly       FPG / PPG

                  Type 1 DM         4-6 times      6th hourly
                                     initially    to 4th hourly
                   Stabilized     Twice a week.    3 samples

                  Pregnancy       Once a week.    FPG / PPG

                 Peri-operative     4-6 times      6th hourly
                                      a day       to 4th hourly

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                             MAGE

                 “Blood Glucose 80 min. after
                  breakfast correlates with MAGE
                  ( Mean Amplitude of Glycaemic
                  Excursions ) throughout the day”


                                           Molnar et. al.

Dr.Sarma@works
                                SMBG
                 •   On intensive insulin therapy
                 •   Diabetes in pregnancy
                 •   IDDM who lack warning symptoms
                     of hypoglycaemia
                 •   Insulin - requiring diabetics
                 •   Diabetics with unusually high/low
                     RTMG.
                 •   Insulin - resistant diabetics on large
                     insulin doses
                 •   Motivated diabetics for tight control.
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                 New era in monitoring control



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