Gestational diabetes (GDM) refers to a high blood sugar level beyond that used to diagnose diabetes, seen for the first time in pregnancy. It is seen in 2-25% of pregnancies, with wide variations in prevalence and incidence among populations. It is important to explore protective and risk factors, especially modifiable lifestyle factors, for this condition.
Study: Maternal caffeine, coffee and cola drink intake and the risk of gestational diabetes – Kuopio Birth Cohort. Image Credit: Photoroyalty / Shutterstock
A new study appeared in Primary Care Diabetes that examined whether coffee/cola drinking and caffeine intake are related to GDM.
GDM is a condition accompanying late childbearing and a high prevalence of obesity. In Finland, where the present study was conducted, over one in five women have GDM. Babies born to such women are more likely to be macrosomic, suffer from neonatal hypoglycemia, and have complicated deliveries or intrauterine complications.
The long-term complications of this condition in the mother include the later development of type 2 diabetes and metabolic syndrome. This is also true of the adult offspring, in addition to obesity.
Coffee drinking is prevalent in Western countries, and the highest levels are seen in Finland, where the average consumption is 9 kg per person per year. The current study was conducted in this country.
Among people who are not pregnant, drinking coffee is linked to a lower risk of type 2 diabetes. This could be via coffee compounds that favor lipid and glucose metabolism. High caffeine and coffee consumption is often part of an unhealthy lifestyle, but the distinct effect of this on GDM risk is unknown.
However, pregnancy recommendations limit caffeine intake to 200 mg daily, that is, one mug or two small cups. This is due to reported associations between caffeine intake in pregnancy and fetal growth restriction (FGR) or small for gestational age (SGA) babies. Studies have shown that moderate total caffeine and coffee intake protect against GDM.
The current study sought to examine how caffeine, coffee, and the consumption of cola drinks were linked to GDM. Data came from the Kuopio Birth Cohort (KuBiCo), which prospectively followed up on pregnant women seen at prenatal clinics in outpatient health centers. All had their babies at Kuopio University Hospital, Finland.
What did the study show?
The study included over 2,000 pregnant women whose diets during the first trimester were reported with the help of a food frequency questionnaire. In most cases, an oral glucose tolerance test was performed between 24 and 28 weeks to diagnose GDM. Approximately one in five of the women were found to have GDM.
Women with GDM were older, with higher body mass index (BMI) and lower weight gain during pregnancy compared to non-GDM women. Their babies tended to be born sooner but weighed more than those born to women without GDM.
The median total caffeine intake was 122 mg/day overall. Among women without GDM vs those with GDM, it was 121 and 125 mg per day. Coffee intake overall and among women without GDM was at 118 mL per day, but among those with GDM, it was higher, at ~130 mL per day.
Cola and energy drink consumption was more prevalent among those with GDM compared to others, though only marginally. However, the mean consumption was 80 mL per day among those with GDM compared to 57 mL per day among the others.
For most women, caffeine comes mainly from coffee. The researchers found that one in three pregnant women had more than the recommended 200 mg of caffeine per day. Moreover, half of coffee drinkers also exceeded this limit. In contrast, 30% did not drink coffee at all during the first trimester.
Moderate coffee consumption showed a small protective association with GDM, the risk being reduced by 13% compared to women who did not drink coffee. While this was observed after adjusting for age-related risk, the effect became non-significant when multiple other confounding factors were accounted for. Therefore, moderate coffee drinking does not affect the risk of GDM.
Caffeine intake in the first trimester did not show any association with GDM.
The opposite trajectory was seen with increased cola consumption. Women who had more than 33.3 mL of cola per day, on average, had an approximately 30% increased risk of GDM after adjusting for multiple factors compared to those who had less than this. This level was chosen as it is the median in this group, which had a low mean consumption level for cola drinks.
The use of sugary cola drinks was not linked to increased GDM risk, but for those who had low-calorie cola drinks, the odds of GDM were 34% higher when adjusted for age but 24% higher after accounting for multiple factors.
What are the implications?
Coffee is commonly consumed, and at high levels, in Finland. This includes three out of four women between 18 and 44 years. One in three pregnancies was linked to excessive coffee consumption, and half the coffee drinkers consumed more than the recommended amount of caffeine.
The only significant association here was with low-calorie cola drinks, and this requires to be replicated in other studies. The lack of protective effect with caffeine or coffee intake, with the known harms of high caffeine intake on fetal growth and pregnancy course, should be considered in future research.
The observation that women with GDM weighed more before the pregnancy but gained less weight during gestation may indicate a successful pregnancy weight management program for women with GDM who are given dietary advice and lifestyle counseling during their prenatal check-ups and via other contacts with public health. Overall, Finland is a good location for research on GDM because of the abundant data gathered by systematic, reliable, and regular screening and treatment extended to almost every pregnant woman in the country.
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