Gestational Diabetes Mellitus-Diagnosis & Treatment

GDM;

by Prof Dr Srimanta Kumar Pal

GD block, PLot 207: Sector III, Kolkata 700 106.

First screening for GDM:--A) a 50 gm of glucose challenge- if reports are abnormal then only one should proceed for two step full OGTT after 100 gm load)for diagnosing GDM.

Two step approach of diagnosis of GDM:-- OGTT  is a diag approach : Diagnostic method of GDM: not screening:- How to do it?? This is one step approach ( 100 gm glucose load  and GTT-- 3 hour straightway .This is not to be confused with  any screening protocol  by 50 Gm,.

B) Prevalence of GDM in India:_ GDM 2% to 6%

C) What is the recurrence risk?? with  chance of recurrence in subsequent pregnancy about 33% if previus preg was GDM.

D) Describe the methodology of performing the test of OGTT:-

There are several methodology to assess glucose tolerance in pregnancy e.g. namely 1) as suggested by American Diabetic Association. They advocate administering 100 gm of gl and then carry out 0 hr, 1 hr, 2 hr. and 3 hr glucose estimating-always by glucose oxidase method not by any other method. 2) Am. College of OB & GYN (ACOG Guideline) also prefers 100 Gm gl. challenge but 3) WHO recommends 75 Gm load (this academic body also administer 75 gm. For men and non preg women too).

E) What is frank DM?

 Any BS level> 200mg / FBS> 126 mg.

F) Severity of glucose intolerance?? We can come across three  kinds of impaired carbohydrate metabolism in pregnancy. Mild degree :_-Impaired Gl Tol during pregnancy only Moderate degree :- Gestational Diabetes ( Type A- controlled with diet only)and type B-which will require drugs as well.) C) Pregestational diabetes.

There is another form diabetes called secondary diabetes due to Pancreatitis, Cystic fibrosis, Cushing’s syndrome, Klinefelter’s syndrome,

G) To whom to Screen? When to screen at what gestation? Not universal screening like Hb% or ABO Rh etc.    In pregnancy the globally accepted policy is to selectively screen pregnant women..  Screen women at first visit only for high risk cases even if she comes at 6-8 weeks of gestation. But cases with moderate risk of GDM then  get the screening test done at 18-20 weeks.

But those who are low risk the screen for GDM is done when she comes for say 4^th visit i.e. at about 28-30 weeks of gestation. This risk stratification is based solely on history only. (Read from internet the Proceedings of fifth international workshop on gestational diabetes mellitus.  Fourth conference which was held in 1997).

 H) What to do if Screen test is + ve after 50 Gm of glucose?? This is called GCT (glucose challenge test)?

Essentially whenever screening test is done it is usually done  after random administration of 50 gm of gluciose intake irrespective of food and time. One will consider is screen +ve if   one hr PPBG  exceeds  130mg (As per Carpenter & Carpenter) or according to some authors if one hr. PPBS (50Gm) crosses 140mg (as per National Diabetic Data Group) . it implies that that preg woman  is screen +.

.I)  What steps thereafter if screen +VE? Proceed for Oral Glucose Tolerance either by 100 Gm GTT/ 75 Gm GTT (Full GTT as it is often called).

Like all other screen test say cervical cytology (Pap Tets) or NT measurement in aneuploidy screening of foetus it does not mean that woman concerned   is harboring Ca Cx or foetus is having aneuploidy (Down’s). 

To confirm the disease it needs to be  glucose intolerance i.e.  one should then proceed for OGTT. Screen + does not mean that she is a case of GDM. The cut off  level of glucose after 100 gm is as follows FBS ( 0 Hr) must be less than 95mg, after 1 hr. < 180mg; 2 nd. Hr sample should be < 155mg and last sample should be < 140 mg

 H) How to interpret the GTT Reports? What are the figures of Euglycaemic women? What will be blood reports???

All four reports are within normal range: Normal figures will be is FBS-95mg, 1 hr-<180mg;   2 hr. PPBS-155 mg and 3 hr gl level should be <140 or now called 130mg.). In such situation she is termed as Euglycaemic.

But if there is family H/O DM, BOH, Obese women /PCOS etc then do not become optimistic. Instead, insist on repeating such GTT on 2 monthly bases.   If one is  practicing in diabetes prone country

Interpretation of Results of OGTT:--

a)                     Now, if any of the four plasma glucose is high, i.e. exceeds the normal stipulated values then she is designated as IGTTP (IMPAIRED GL. TOL. IN Pregnancy and not GDM. I strongly feel that, such cases will be benefited by some Dietary interventions and Exercises .Hopefully one parameter abnormality will not affect foetus adversely but in my opinion, that particular women needs two monthly PPBS estimation and possibly HBA1C assessment. This is my personal feeling, not recommended by any international authority.

.3) if Two Reports are high?

 Those women who exhibit glucose levels which exceed the stipulated figures on two occasions in 100 gm OGTT (Normal figures as mentioned earlier are  FBS-95mg, 1 hr-<180mg; 2 hr. 155 mg and 3 hr gl level should be <140/130mg.)  Two high levels of raised glucose value in OGTT (say 1 hr & 3 Hr,-both are of raised values,   or 1 hr and 2 nd. hr both are raised) -then she should be leveled as GDM. Please do remember my dera members , that to qualify for frank DM on blood glucose must exceed 200mg or HBA1C > 8.

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L) Who are high risk women to develop GDM?? Beware of GDM in following cases (high risk cases) e.g. 1) If prepreg body wt is high, 2) P/H/O PIH  3) P/H/O Cong. Malformed foetus,4)  PIH,5)  F/H/O DM. 6) Age >28 yrs, 7) prior GDM, 8) persistent GLYCOSURIA, Polyuria with no e/o UTI, 9) unexplained IUFD, 10) Hydramnios, Polyhydramnios in current preg., Any developing foetal soft markers in USG in current preg (kindly read this soft markers in details- pl. excuse me for advising u).

M_ ) What is the Target glucose level while in medical therapy in cases with GDM? DM?

HBA1C < 7 better, PREFERABLY  6; Self monitoring at home is recommended. Try to encourage your pts. Target nowadays is very strict than earlier. May be six times monitoring per day in established DM, not for GDM cases ,  particularly in case who are ion insulin Ry. 

N) What is the  Therapeutic Target?: Ans:-FBS/Prelunch: somewhere plasma glucose 70-105mg; 130 mg 2 hr after meals. Such corresponding  level should be equivalent to 60-95 mg and 120 mg if one send whole blood i.e. unclotted to Lab.

o) Also assess: - Urinary proteins, serum creatinine, and uric acid as needed. To watch for Macrosomia/CM of foetus in case of overt DM. Nowadays one  can treat GDM by oral agents like Metformin/Gluburide.

ode admn is not contraindicated. Minipill will be safe to use in P.P period as contraception. Long term follow up (life long) 3 yearly PPBS will be judicious.