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Introduction
Diabetes mellitus (DM) is a metabolic disorder of multiple aetiology,
characterised by chronic hyperglycemia which is associated with
disturbances of carbohydrate, fat and protein metabolism. This
disorder results from a defect in insulin secretion, insulin action
or both (1).
Diet in combination with lifestyle changes such as regular exercise
helps patients with diabetes to lose weight and to also improve
their overall metabolic control (2,3,4). The rst documented dietary
prescription in the treatment of presumed diabetes appeared in
the Papyrus Ebers, written around 1500 BC (5). High carbohydrate
diets produce a marked rise in post-prandial glucose, especially
if rened or if it has a low bre (6). Complex carbohydrate,
Turkish Journal of Endocrinology and Metabolism, published by Galenos Publishing.
Original Article
Purpose: Dietary modication in association with life style changes is important in the management of the diabetes. Cereals account for as much
as 77% of total caloric consumption in most African diets. Corn which is the largest cultivated cereal crop in Nigeria is prepared as a meal in many
forms. The objective of this study was to assess the glycaemic responses to different preparations of corn meals.
Material and Method: The design was a quasi-experimental with a total of 32 participants, 16 subjects with type diabetes and 16 age-and
sex-matched non-diabetic control subjects. After an overnight fast, the participants were given corn meals to eat and had their blood sample
collected every 30 minutes for over a 2 hour period for the assessment of blood sugar level and estimation of glycaemic responses. This was
repeated weekly till the glycaemic index (GI) and plasma sugar level response to the different test corn meal preparation, such as boiled corn,
roasted corn, pap and cornakes had been assessed.
Results: All the different corn meal preparations had high GI, with corn akes having the highest GI and pap the lowest. The GI for the corn meals
in the non-diabetic were; pap 71.7±14.4%, roasted corn 76.5±14.9%, boiled corn 82.2±14.9% and cornakes 88.1±14.4%.
Discussion: Methods of preparing a meal from corn affect glycaemic response.
Turk Jem 2015; 19: 79-82
Key words: Glycaemic index, corn meal, type 2 diabetes, Nigeria
Amaç: Yaşam tarzı değişiklikleri ile birlikte diyet değişiklikleri diyabet tedavisinde büyük öneme sahiptir. Tahıl çoğu Afrika diyetinde toplam kalori
tüketiminin %77 kadarını oluşturmaktadır. Mısır Nijerya’da en çok ekilen tahıl türüdür ve çeşitli biçimlerde yemek olarak hazırlanır. Bu çalışmanın
amacı, farklı mısır yemek tarzlarına glisemi yanıtlarını değerlendirmektir.
Gereç ve Yöntem: On altı diyabetik hasta ve 16 yaş ve cins uyumlu non-diyabetik kişi olmak üzere toplam 32 hasta yarı-deneysel tasarımlı bu
çalışmaya alındı. Bir gecelik açlığı takiben katılımcılara mısır yemekleri verildi ve kan şekerini ve glisemik cevabı tespit etmek için 2 saat boyunca
her 30 dakikada bir kan örnekleri alındı. Haftada bir bu işlem haşlanmış mısır, kavrulmuş mısır, pap ve mısır gevreği gibi farklı mısır yemekleri
için tekrarlandı.
Bulgular: Mısır gevreği en yüksek, pap en düşük glisemik indekse (GI) sahip olmak üzere tüm mısır yemek çeşitleri de yüksek glisemik indekse
sahipti. Non-diyabetiklerde mısır yemeklerinin GI’leri şöyleydi; pap %71,7±14,4, kavrulmuş mısır %76,5±14,9, haşlanmış mısır %82,2±14,9 ve mısır
gevreği %88,1±14,4.
Tartışma: Mısırdan hazırlanan farklı yemekler mısırın glisemik cevabını etkileyebilir.
Turk Jem 2015; 19: 79-82
Anah tar ke li me ler: Glisemik indeks, mısır unu, tip 2 diyabet, Nijerya
Address for Correspondence: Akinola Dada MD, Lagos State University Faculty of Medicine, Department of Internal Medicine, Lagos, Nigeria
Phone: +234 802 309 64 27 E-mail: akindudu2004@yahoo.ca
Received:
16/11/2014
Accepted:
14/02/2015
Akinola Dada, Anthonia Ogbera, Sunday Ogundele*, Olufemi Fasanmade, Augustine Ohwovoriole**
Lagos State University Faculty of Medicine, Department of Internal Medicine, Lagos, Nigeria
*Lagos State University Faculty of Medicine, Department of Pharmacology, Lagos, Nigeria
** Lagos University Faculty of Medicine, Department of Internal Medicine, Lagos, Nigeria
Glycaemic Responses to Corn Meals in Type 2 Diabetics and
Non-Diabetic Controls
Tip 2 Diyabetikler ve Non-Diyabetik Kontrollerde Mısır Yemeklerine Glisemik
Cevaplar
DOI: 10.4274/tjem.2877
Abs tract
Özet
79
vegetables, fruits and soluble and viscous bers like pectin found
in legumes are more effective in achieving normal plasma glucose
and lipid levels than the insoluble ber such as cellulose found in
cereals (6,7). Cereals account for as much as 77% of total caloric
consumption in most African diets (8,9). Cereal grains include
wheat, rice, corn, barely, millet, oat and rye; of these, corn is by far
the largest cultivated cereal crop in Nigeria (10). Corn is prepared
as a meal in many forms; it can be boiled, roasted or processed
and then prepared as pap or as cornakes. Corn meals serve as
an important source of carbohydrate. Studies have shown that
the metabolic response to various foods in patients with type 2
diabetes differs from that in non-diabetic persons (7).
Corn as a meal has a high glycemic index (GI) (11), but studies
have shown that when meals are prepared in different forms from
a major ingredient they produce different glycemic responses.
We therefore decided to assess the glycemic responses to the
different forms of preparations of corn meal (12,13). The main
objective of this study was to assess the potential role of corn
meals in the dietary management of DM, by determining the
glycemic response of various corn meals preparation in patients
with type 2 diabetes and compare this to the response in non-
diabetic controls.
Materials and Methods
The study was carried out at the Endocrinology and Metabolism
Unit of Medicine Department of Lagos University Teaching
Hospital. The study design was quasi-experimental interventional
study with a total of 32 subjects. Sixteen subjects with type 2
diabetes attending the endocrinology clinic of the hospital that
consented and met the inclusion criteria were matched for age
and sex with sixteen non-diabetic controls who were members of
staff in the hospital, including medical students. The study had a
cross-over period of one week during which each subjects served
as their own internal control for the different preparation of corn
meals that were assessed. The different corn meal preparations
were boiled corn, roasted corn, cornakes and pap.
At enrollment, all subjects were clinically examined and their
anthropometric measurements were recorded. Male and female
type 2 diabetics with good glycemic control on diet alone or diet
with oral hypoglycemic agents and aged between 20 and 50
years were included in the study. Subjects, who were obese,
with BMI ≥30 kg/m2, type 1 diabetic, all insulin-treated type 2
diabetics, patients with history or evidence of chronic complication
like gastro-paresis were all excluded. Healthy volunteers who
were not currently on any drug known to affect carbohydrate
metabolism, with no known family history of diabetes mellitus,
BMI <30 kg/m2 and aged between 20 and 50 years were
also included in the study. The protocol was submitted to the
institutional ethics committee for review and approval.
The test meals were prepared by the dietetics unit of the hospital.
The meals and ingredients were bought at the same time,
from the same source and prepared by the same dietitian. The
components of the meals were calculated from food tables to
provide equivalent 50 g of carbohydrate (13). Pap was prepared
from corn our. A single brand of cornakes was bought from
open market and about 50 g carbohydrate equivalent portion was
calculated from the food table on the pack. Boiled and roasted
corn meals were prepared from fresh corn as appropriate.
All the 32 participants, 16 type 2 diabetics and 16 non-diabetics
subjects took different meal each test day of the week till all the
different meals had been tested over a four week period. All the 16
non-diabetic subjects took an oral glucose tolerance test (OGTT) with
50 g of anhydrous glucose at the start of the study after they had been
on unrestricted diet containing at least 150 g of carbohydrates per
day for at least 72 hours prior to the test. They were also requested
to abstain from smoking, strenuous physical activity and ingestion
of alcohol 2 days before the test. All participants were requested
to observe an overnight fast before taking the test meal, diabetic
subjects were told to take their usual doses of oral hypoglycemic
agents during the study period. Subjects on glibenclamide or
rosiglitazone took the medication 30 minutes before study meals
consumption while those on metformin took the drug at the end of
meal consumption. The participants were made to sit and rest for
at least 30 minutes before commencement of the test procedures.
An indwelling cannula was kept patent with heparinized saline
was introduced into a forearm vein of each participants. Baseline
blood samples for fasting blood glucose were then taken from each
subject. Test meals were served warm in disposable plates and
consumed over a period of 10-15 minutes followed by drinking 250
ml of water. Blood samples were collected at half hourly intervals for
two hours for the measurement of plasma glucose.
The software used for the analysis was SPSS (version 16),
quantitative variables were expressed as mean + standard error
of mean (mean + SEM). The differences between means were
tested with Student’s t test. The level of statistical signicance was
taken as p value ≤0.05.
Results
The results showed that the participants in the two groups were
similar in their demographic and anthropometric proles except
for the mean waist circumference which was signicantly higher in
participants with diabetes compared with non-diabetics subjects.
Two female diabetics and two female non-diabetics dropped
out during the study period due to discomfort from repetitive
venipuncture and the inconvenience of follow-up (Table 1).
The mean fasting plasma glucose (FPG) level for non-diabetic
subjects assessed before serving them the test meals were within
the normal limits (<110 mg/dl), the levels among the diabetic
subjects were higher compared with non-diabetics. Cornakes
had the highest post-prandial glucose response among all the
corn meals. The plasma glucose levels peaked at 60 minutes
for all test meals in the non-diabetics and the 2 hour postload
glucose (2HPPG) levels were comparable to the corresponding
FPG levels, see Figure 1.
The calculated GI for the corn meals in the non-diabetic was as
follows: pap: 71.7% (±14.4), roasted corn: 76.5% (±14.9), boiled corn:
82.2% (±14.9) and cornakes: 88.1% (±14.4). The plasma glucose
response indices showed that pap has best prole with the least
maximum increase in plasma glucose and least incremental area
under glucose curve (IAUC) among subjects with diabetes (Table 2).
80
Turk Jem 2015; 19: 79-82
Dada et al.
Glycaemic Responses to Corn Meals in Type 2 Diabetics and Non-Diabetic Controls
81
Discussion
The study demonstrated that corn meal in its different forms has a
high GI and that the GI for corn meal differs according to how the
meal is prepared. This nding is important because it will guide
health care workers involved in the management of patients with
diabetes to make appropriate recommendation on the best way
to prepare corn meals for dietary control and management of
diabetes. GI is the extent to which a test food raises the blood
glucose level compared to how much the level is raised by an
equivalent amount of pure glucose (14,15). GI is determined by
calculating the ratio of the IAUC for a reference meal (usually 50
g of pure glucose) to that of an equivalent amount of a test meal
(16,17). A food is considered to have a high GI if its response is
more than half the value of that of glucose (12). The classication
of GI is as follows; low GI: <55%, medium GI: 55-69% and high
GI: >70%.
Knowing the GI of a food is important because diet has been
implicated in the aetiology of type 2 diabetes among people
with high risks for the disease (18). Caloric intake in excess of
requirements is known to contribute to developing obesity which
is a known risk factor for the disease (18). The different GI of various
corn meal preparations is lowest for pap, this is prepared from a
processed corn our and highest for cornakes another processed
corn product. Cornakes have the highest peak plasma glucose
and the highest maximum increase in plasma glucose which
suggests that cornakes are not ideal meal for diabetics. Among
the non-diabetics, cornakes also had worse glycemic prole. The
better GI of pap compared to the other corn meal preparations
may be explained by the fact that it has a low fat, calorie and ber
content. This may be due to the various steps in its processing such
as steeping, milling and sieving which lead to substantial nutrient
loss. Much of the protein in cereal grains is located in the testa and
germ which are usually sieved off during processing. Studies have
shown that processing grains modies their glycemic index proles
(19,20). Milling of wheat serves to separate them into different
components such as bran, germ and endosperm producing a
nely ground our (21,22). Bread made from nely ground whole-
meal our has a GI of 71±2%, this average was from 13 different
studies, and it is not different from the GI of white bread (23). In
contrast, bread containing a substantial proportion of whole or
cracked wheat kernels has a GI some 20-30% lower than white
bread (23). In a study by Fasanmade and his co-worker in Ibadan,
South-Western Nigeria, they reported that the GI for maize our
Turk Jem 2015; 19: 79-82
Dada et al.
Glycaemic Responses to Corn Meals in Type 2 Diabetics and Non-Diabetic Controls
Table 2. Glycemic response indices of corn meals in persons
among diabetic and non-diabetic participants
Mean (SEM)
PGRI Non-diabetic Type 2 diabetics P value
Cornakes
PPG (mg/dl) 129.6 (5.4) 199.8 (5.4) 0.00001`
MIPG (mg/dl) 45 (5.4) 73.8 (5.4) 0.00172
IAUGC (mmol*min/l) 157.4 (26.2) 292.6 (26.3) 0.00089
Roasted Corn
PPG (mg/dl) 115.2 (5.4) 160.2 (9) 0.00005
MIPG (mg/dl) 36 (3.6) 55.8 (9) 0.00127
IAUGC (mmol*min/l) 125.3 (19) 217.4 (27) 0.00199
Boiled Corn
PPG (mg/dl) 111.6 (9) 1692 (9) 0.00007
MIPG (mg/dl) 37.8 (5.4) 48.6 (5.4) 0.18911
IAUGC (mmol*min/l) 114.3 (16.2) 181 (16.2) 0.00746
Pap
PPG (mg/dl) 117 (5.4) 169.2 (7.2) 0.00001
MIPG (mg/dl) 37.8 (5.4) 48.6 (5.4) 0.02717
IAUGC (mmol*min/l) 121 (12.7) 186 (25) 0.02022
PGRI: Plasma glucose response indices, MIPG: Maximum increase in plasma
glucose, PPG: Peaked plasma glucose, IAUGC: Incremental area under glucose
curve
Table 1. Baseline characteristics of diabetics and non-diabetics
participants
Characteristics Means (SEM)
Non diabetic Type 2 diabetic P value
Sex
Male 6 5
Female 10 11 0.7
Age (years) 44.9 (1.7) 44.6 (1.7) 0.9
BMI (kg/m2)26.1 (0.8) 25.3 (0.8) 0.5
Waist circumference (cm) 82.7 (2.4) 93.1 (2.4) 0.001
WHR 0.88 (0.02) 0.9 (0.02) 0.3
Duration of DM (months) -78.8 (19.6)
BMI: Body mass index, WHR: Waist circumference to hip ratio, DM: Diabetes
mellitus
Figure 1. Baseline and the timed glycaemic proles of subjects with
diabetes and non-diabetics to different preparation of corn meal
82
was 54.83±26.74% and 26.61±11.33% in diabetic and non-diabetic
subjects, respectively (16). The GI was lower than the 71±14.4%
recorded in non-diabetics in our study. This may be explained by
the fact that the meal prepared from maize our in their study was
served with a soup of a vegetable leaf specie (Corchorus olithorus),
tomato sauce and 25 g of boiled beef meat (16). In another study
in Philippines on healthy volunteers, the GI for boiled corn meal
prepared from a variety of maize known as the quality protein
maize was 80.29±17.11%. The nding in the Philippines study is
similar to the result of GI for boiled corn in our study which was
82.2±14.9% (24). Ekpebegh in his work on assessment of glycemic
response to meals prepared from sorghum and maize among
Nigerian males reported that glycemic response to these meals
was attenuated because they were prepared mixed with bean
products (25). These effects are probably due to the high ber
content in the bean covering like in all legumes (13,26).
The nding that the FPG and the 2HPPG levels in all the non-
diabetic subjects were within normal range conrmed that they
were all glucose tolerant. The mean fasting glucose levels in
subjects with diabetes were also within normal range. This is
explained by the fact that they were all well-controlled on their
regular doses of oral hypoglycemic agents.
Different methods of preparing corn meal affect its glycemic
response. This study showed that cornakes may not be an
ideal corn meal preparation for diabetics; it had the highest
glycemic response among all the tested corn meal preparations.
Its consumption should be in a measured quantity. Pap had the
lowest GI and we therefore recommend it as the ideal corn meal
preparation. In line with the reports from other studies, taking corn
meal mixed with vegetables lowers their glycemic response and
should be the preferred form of serving the meal.
Acknowledgments
This work was part of a dissertation submitted to the National
Postgraduate Medical College of Nigeria in partial fulllment of
the requirements for the award its Fellowship in Internal Medicine
with sub-specialization in Endocrinology and Metabolism.
Ethics Committee Approval: It was taken, Informed Consent: It
was taken, Concept: Akinola Dada, Sunday Ogundele, Olufemi
Fasanmade, Anthonia Ogbera, Augustine Ohwovoriole, Design:
Akinola Dada, Olufemi Fasanmade, Anthonia Ogbera, Augustine
Ohwovoriole, Data Collection or Processing: Akinola Dada,
Sunday Ogundele, Olufemi Fasanmade, Augustine Ohwovoriole,
Analysis or Interpretation: Akinola Dada, Sunday Ogundele,
Olufemi Fasanmade, Anthonia Ogbera, Prof Ohwovoriole,
Literature Search: Akinola Dada, Sunday Ogundele, Writing:
Akinola Dada, Sunday Ogundele, Olufemi Fasanmade, Augustine
Ohwovoriole, Anthonia Ogbera, Peer-review: External and
Internal peer-reviewed, Conict of Interest: No conict of interest
was declared by the authors, Financial Disclosure: The authors
declared that this study has received no nancial support.
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