Gestational diabetes mellitus (GDM)
By gestational diabetes mellitus we mean any form of glucose intolerance (and of any degree) that arises during pregnancy (hence the synonym "diabetes mellitus"); gestational diabetes occurs most frequently between the 10th and 14th week of pregnancy and very often is attributable to type 2 diabetes mellitus triggered by the metabolic changes typical of the gestation itself.
NB . Gestational diabetes is very often related to a family history of type 2 diabetes mellitus.
Gestational diabetes is a condition that is quite common and should not be underestimated; in addition to "becoming chronic", worsening the mother's state of health even after giving birth, gestational diabetes can compromise fetal development to the point of causing neonatal death. It is therefore deducible that the control of risk factors, the monitoring of values in pregnancy and the early diagnosis of gestational diabetes are necessary precautions to reduce its morbidity.
Risk factors for gestational diabetes: obesity, family history of diabetes mellitus, glycosuria, previous gestational diabetes and age> 25 years.
During pregnancy it is normal that, starting from the 3rd month, there is a certain reduction in glucose tolerance; to verify that the change is physiological and not pathological, it is necessary for the pregnant woman to start a glycemic screening procedure by means of the "50g glucose test" which, if successful, requires further investigation with the "100g test glucose".
NB . Gestational diabetes (which occurs during pregnancy) MUST be well differentiated from that of PREVIOUS conception (therefore already present before pregnancy), better defined as "diabetes mellitus in pregnancy".
Diet
Summarize in a few lines the guidelines for a good and healthy diet during pregnancy (even more important in the case of gestational diabetes), it is not easy; we will therefore try to be exhaustive but at the same time specific, mainly dealing with the energy aspects and the distribution of macronutrients.
Let us begin by pointing out that, if we consider obesity as the top risk factor, to minimize the occurrence and the development of gestational diabetes, it is first of all necessary to normalize body weight BEFORE the beginning of pregnancy. This can be applied in a "planned" situation, remembering that: to lose weight while remaining healthy it is necessary to lose NOT more than 3kg per month (ergo, maximum 36kg per year). It follows that, in an obese object, normalizing weight in order to reduce the risk of gestational diabetes may require a substantial postponement of the pregnancy itself.
Also during pregnancy it is FUNDAMENTAL to monitor (better if weekly) the weight gain; the increase in weight for an obese pregnant woman (<or = 7kg) must be less than that of a person who is overweight (7-11.5kg), normal weight (11.4-16kg) or underweight 12.5-18kg ) ... but this does not mean that generalized weight loss occurs during gestation, as this would prevent the proper development of the unborn child!
The caloric needs of a person with gravidic diabetes (on average) should NOT exceed 30-32 kcal for each kg of desirable physiological body weight; therefore, from the 2nd MONTH onwards, the pregnant woman must take an energy-daily amount proportional to her state of nutrition: for an obese or overweight person it is + 200kcal / day, for a subject in normal weight it is + 300kcal / day and for an underweight subject is + 365kcal / day.
NB . In the case in which the pregnant woman must remain at complete rest (semi-lodging), for the obese or overweight subjects the caloric surplus must be around 100kcal / day.
In the case of gestational diabetes, the protein proportion of the diet remains unchanged: approximately 13% of the total kcal + 6g, or 1.3-1.7g per kg of desirable physiological body weight. The lipid portion is even proportionally equal to the normal portion, or 25% of the total kcal, even if, more in the diabetic than in the healthy one, it would be appropriate to keep saturated fat levels at 7-10% and favor the intake more. of monounsaturated and essential fatty acids (ω ‰ 3 = 0.5% of kcal tot and ω ‰‰ 6 = 2% of kcal tot).
Before tackling the estimate of dietary carbohydrates, let us remember that diabetes mellitus is a metabolic disease that induces reduced glucose tolerance and often reduced insulin secretion, therefore in food therapy it is extremely important to evaluate:
- The glycemic load of 6 daily meals
- The glycemic index of foods.
Unfortunately it is NOT possible to excessively reduce the portion of total carbohydrates, as they are necessary for the energy processes of the fetus, but it is nevertheless desirable to reduce them to the minimum necessary to favor the restoration of a satisfactory metabolic condition.
If in a healthy and sedentary subject, the nutritional distribution is approximately: 13% proteins, 25-30% lipids and 62-57% carbohydrates ... in healthy pregnant women it becomes 13% + 6g proteins, 25-30% lipids and that which remains carbohydrates. In my opinion, in addition to preferring foods with the lowest glycemic index, in gestational diabetes it is essential to "reduce" the portion of simple carbohydrates (not exceeding 8-10%, against 12% of the healthy subject) and increase fat and protein intake up to the upper limit of the recommended. Let's take an example:
Pregnant with gestational diabetes, 6th month, BMI 29.4 for a weight of 78kg (physiological weight 55kg)
- Energy requirement 32kcal * 55kg (desirable weight) = 1760kcal (which corresponds to the normal energy + 200kcal of pregnancy in the presence of overweight).
- Proteins, two calculation methods:
- (13% of 1760) + 6g = 63.2g
- 1.3g * kg of physiological weight (55) / energy protein coefficient (4) = 71.5g
In this case, in order to keep the overall carbohydrate share to a minimum, we choose the 2nd method!
NB . A coefficient of 1.3 was chosen, but as already specified above, it is also possible to reach 1.7g / kg of desirable physiological body weight.
- Lipids: between 25% and 30%, we choose 30% to keep the overall carbohydrate share to a minimum, with the simple trick of keeping saturated fats at 7-10% and drastically increasing the proportion of essential and monounsaturated fats ( task of the dietitian): 30% of 1760kcal / lipid energy coefficient (9) = 58.7g
- TOTAL Carbohydrates: calculated on the remaining energy, excluding lipids and proteins from the total intake: 1760kcal - energy proteins (286kcal) - fat energy (528kcal) / carbohydrate energy coefficient (3.75) = 252g
NB . The share of simple carbohydrates must remain around 8-10% (task of the dietician).
Obviously it is not the intention of this article to "simplify" or provide the tools necessary to compose the diet of a gestational diabetic, the concepts to be taken into account are many more and this represents a complex job even for a professional. However, for those at risk, I believe it may be helpful to have a general overview of the real needs related to a disorder so widespread and as serious as gestational diabetes.
Bibliography:
- DIABETES MELLITUS: Diagnostic and Therapeutic Criteria: an update - CM Rotella, E. Mannucci, B. Cresci - SEE Florence - pag 43:45
- Manual of clinical nutrition - R. Mattei - Medi Care - Franco Angeli - pag 407: 409.
