Department of Internal Medicine, National Hospital Organization Matsumoto Medical Center Matsumoto Hospital, 2-20-30 Minami, Murai, Matsumoto 399-8701, JapanJapan
Department of Nutrition Management, National Hospital Organization Matsumoto Medical Center Matsumoto Hospital, 2-20-30 Minami, Murai, Matsumoto 399-8701, JapanJapan
Also available as PDF (figures and tables appear in the PDF).
Carbohydrate counting is a meal planning approach for diabetic patients, but individual variations of the effect of glycemic index do not seem to be well taken into account. Here we assessed glycemic variations after the ingestion of different carbohydrate-containing foods by continuous glucose monitoring in healthy and diabetic individuals in daily life. After an overnight fast, seven healthy persons and four patients each of type 1 and 2 diabetes were instructed to eat three different kinds of 40 g carbohydrate-containing breakfast within 10 minutes for three consecutive days. The meals consisting of foods chosen from starchy foods, fruits and dairy foods were 100 g cooked rice with Japanese green tea seasoning (183 kcal), 300 g apple (162 kcal), and 35 g cereal with 180 ml milk (253 kcal), respectively. The glycemic profiles were measured every 5 minutes over three hours before and after the breakfast meals by using a continuous glucose monitoring system (iPro2®). Sulfonylurea was not taken, and insulin dose was reduced at the breakfast to avoid hypoglycemia, which was fixed during the study. The respective profiles of glycemic responses to the breakfast meals varied largely among individuals, especially in diabetic patients. The sums of glycemic increments over three hours after the ingestion of apple and cereal+milk (322 ± 123 (mean ± SD) and 181 ± 275 mg/dl) were significant (p<0.05) lower than those after the rice ingestion (543 ± 209 mg/dl) in healthy persons, but there was no significant difference among those (528 ± 471, 766 ± 1374 and 1442 ± 1025 mg/dl, respectively) in diabetic patients. Postprandial glucose levels were suppressed in the cereal+milk meal, but the elevated glucose levels appeared to persist in patients with type 1 diabetes. Medical staff should be aware of controlling carbohydrate intake with glycemic index, keeping in mind large individual variations of glycemic responses to the same amount of carbohydrate. It may be wise for diabetic patients to develop their own personal glycemic indexes in their respective situations.
Keywords: Carbohydrate counting; Glycemic index; Rice; Apple; Milk; Continuous glucose monitoring; Apple; Milk
Figure 1 shows individual glycemic profiles after the
ingestion of three different kinds of, but the same amount (40 g)
of carbohydrate-containing foods (rice, apple and cereal+milk)
for breakfast in 7 healthy individuals (A to G) as in Table 1. The
glycemic profiles were assessed every 5 minutes over 3 hours
by a continuous glucose monitoring system at home. Similarly,
Figure 2 shows those in four T2DM patients (A to D) and those
in four T1DM patients (E to H). The patients A to D consistently
took 50 mg sitagliptin, nothing, 50 mg sitagliptin + 250 mg met-
formin, and 50 mg sitagliptin + 250 mg metformin, respectively,
after the breakfast meal intake. The patients E to H injected bolus
insulin before the meal intake, doses of which were reduced and
fixed at 2U, 5U, 5U and 3U, respectively. The respective profiles
of blood glucose responses to three different meals for breakfast
varied largely among individuals, especially in diabetic patients.
However, as expected, a rise in blood glucose levels was, on the
whole, higher after the rice ingestion than after ingestion of the
other two meals (apple and cereal+milk).
Incremental area of postprandial glucose levels after
the ingestion of three different meals shown in Figures 1 and 2
is depicted as a mean+ or –SD of sums of every 5-minute blood
glucose level minus baseline level at time 0 in 7 healthy persons
1442 ± 1025, 528 ± 471 and 766 ± 1374 mg/dl, respectively.
Similarly, those at the time interval of 0 to 60 minutes were 154
± 108, 148 ± 69 and 121 ± 122 mg/dl in healthy persons, and 420
± 197, 360 ± 264 and 184 ± 196 mg/dl in diabetic patients; those
at the time interval of 60 to 120 were 286 ± 108, 163 ± 92 and 92
± 155 mg/dl in healthy persons, and 680 ± 390, 363 ± 306 and
442 ± 645 mg/dl in diabetic patients; those at 120 to 180 were
104 ± 132, 11 ± 59 and -31 ± 105 mg/dl in healthy persons, and
342 ± 612, -193 ± 275 and 141 ± 675 mg/dl in diabetic patients,
respectively.
In healthy persons, glycemic increments were sig-
nificantly (p<0.05) smaller after the ingestion of apple and
cereal+milk than after the rice ingestion at the time interval of 0
to 180 minutes. At the time interval of 60 to 120, the increments
after the cereal+milk ingestion were significantly (p<0.05)
smaller than those after the rice ingestion. In diabetic patients,
the increments after the cereal+milk ingestion at the time inter-
val of 0 to 60 minutes and after the apple ingestion at the time
interval of 120 to 180 minutes were smaller than those after the
rice ingestion at the respective time intervals. The mean value
of the sums after the cereal+milk ingestion in healthy persons
and that after the apple ingestion in diabetic patients at the time
interval of 120 to 180 minutes were below the baseline. When
glycemic indexes were calculated with rice as a reference (100)
using the mean values at the time interval of 0 to 180 minutes
in this study, those of apple and cereal+milk were 59 and 33
in healthy persons, and 37 and 53 in diabetic patients. Using
the mean values at the time interval of 0 to 120 minutes, those
were 71 and 48 in healthy persons, and 66 and 57 in diabetic
patients.
When diabetic patients were divided into two groups glucose levels were measured every 5 minutes over 3 hours by a continu- (T1DM and T2DM, n=4 each), mean values of incremental
blood glucose levels (Δ Mean Blood Glucose) after the ingestion
of three different meals (rice (A), apple (B) and cereal+milk (C))
in three groups of T1DM, T2DM and Control (7 healthy persons)
are depicted in Figure 4. The mean value in A was the highest
in T1DM, intermediate in T2DM, and the lowest in Control at
every 5-minute time point. Compared with this, the mean value
in B was higher in T1DM and T2DM than in Control during a
shorter period of time. The mean value of postprandial glucose
In the present study, we assessed glycemic variations
after the ingestion of three different kind of, but the same amount
of carbohydrate-containing meals, chosen from starchy foods,
fruits and dairy foods, by using continuous glucose monitoring in
healthy and diabetic individuals in daily life. The rice meal con-
tained protein, and the cereal+milk meal contained protein and
fat as a combination of foods. Individual variations of glycemic
responses to these meals were considerably large, especially in
diabetic patients, although less accuracy of continuous glucose
monitoring at home should be taken into account.18 However, the
average glycemic excursions appeared to be more or less similar 2-5 to those in previous reports2-5 in view of glycemic index. In both
the groups, it was indicated that glycemic indexes of apple and
cereal+milk were approximately 35 to 70.
Fruits generally belong to low glycemic index foods,
as they are rich in dietary fiber and contain fructose and glu-
cose moieties. It has been demonstrated that glycemic indexes
of several kinds of fruits were approximately the same between
healthy persons and type 2 diabetic patients.19 According to In-
ternational Tables of Glycemic Index, 2008,4 glycemic indexes
of fructose, sucrose and apples are 15, 65 and 36, respectively.
In our study, postprandial glucose levels after the apple ingestion
were lower than those after the rice ingestion, and returned to or 2 (T2DM, n=4) and type 1 (T1DM, n=4) diabetic patients.
often decreased below the baseline, as had been shown in the 5,19 other reports.5,19 Such a pattern of postprandial glucose levels is
suggested to be linked to increased appetite and weight gain,20
which seems to be one of hints on nutrition education. However,
the restriction of fruit intake had no effects on HbA1c level or
weight loss in type 2 diabetic patients.21 The consumption of fruit
juice seems to have no overall effects on fasting blood glucose
and insulin levels.22
Glycemic indexes of milk and yogurt are 39 and 41,
respectively, in the International Tables.4 In addition to lactose
providing fewer glucose moieties than the same amount of
maltose or starch, dairy protein, especially the whey protein, 23-26 can stimulate glucagon-like peptide 1 and insulin secretion, 3,27-31 and dairy fat and organic acids can delay gastric emptying.
Along with these observations, the present study showed sums
of glycemic increments after the ingestion of common breakfast
cereal (corn flakes) of a high glycemic index together with milk
(or yogurt in T1DM 4) were significantly lower than those after
the rice ingestion. Interestingly, persistent elevated glucose lev-
els were seen in type 1 diabetic patients, excluding one who had
hypoglycemia after the cereal+milk ingestion due to an acciden-
tal hard labor. Oestman et al.27 previously presumed that milk
may produce a higher glycemic index when tested in individuals
with diminished or absent β cell function than in healthy subjects
capable of responding to the insulinotropic components in milk.
Our finding seems to be consistent with this presumption.
Thus, it was clearly demonstrated that inter-individual
variations of postprandial glucose levels after the ingestion of
different carbohydrate-containing foods were large in healthy
and, especially, in diabetic individuals in daily life. Neverthe-
less, the average profiles of the glucose levels approximately
accorded with those previously reported. The glucose levels
slowly rose after dairy meals, and the elevated levels persisted
in type 1 diabetes. Medical staff should be aware of controlling
carbohydrate intake with glycemic index, keeping in mind large
individual variations of glycemic responses to the same amount
of carbohydrate, due to the impact on glycemia of dietary com-
ponents and non-dietary factors.1 It may be wise that diabetic
patients are advised to develop their own personal glycemic in-
dexes in their respective situations.
The authors declare that they have no conflicts of interest.
This study was in part supported by a research grant from Poli-
cy-Based Medical Service Foundation, Japan.