Strategy for early identification of prediabetes in lean populations: New insight from a prospective Chinese twin cohort of children and young adults

Incidence and temporal trends in type 2 diabetes by weight status: A systematic review and meta-analysis of prospective cohort studies

Background

Diabetes is more prevalent among overweight/obese individuals, but has become a significant public health challenge among normal weight populations. In this meta-analysis, we aimed to estimate diabetes/prediabetes incidence and its temporal trends by weight status.

Methods

PubMed, Embase, Web of Science, and Cochrane Library were searched until 8 December 2021. Prospective cohort studies reporting diabetes incidence by baseline body mass index (BMI) categories in adults were included. The median year of data collection was used to assess the temporal trends. Subgroup analyses and meta-regression were also performed.

Results

We included 94 studies involving 3.4 million adults from 22 countries. The pooled diabetes incidence in underweight, normal-weight, and overweight/obese adults was 4.5 (95% confidence interval (CI) = 2.8-7.3), 2.7 (95% CI = 2.2-3.3), and 10.5 (95% CI = 9.3-11.8) per 1000 person-years, respectively. The diabetes incidence in low- and middle-income countries (LMICs) was higher than in high-income countries among normal-weight (5.8 vs 2.0 per 1000 person-years) or overweight/obese (15.9 vs 8.9 per 1000 person-years) adults. European and American regions had a higher diabetes incidence than the non-Western areas, regardless of weight status. Underweight diabetes incidence decreased significantly from 1995-2000 to 2005-2010. Diabetes incidence in normal-weight populations has increased continuously since 1985 by an estimated 36% every five years. In overweight/obese adults, diabetes incidence increased between 1985-1990 and 1995-2000, stabilised between 2000 and 2010, and spiked suddenly after 2010.

Conclusions

Diabetes incidence and its temporal trends differed by weight status. The continuous upward trend of diabetes incidence among overweight/obese individuals requires urgent attention, particularly in LMICs. Furthermore, diabetes among normal-weight individuals is becoming a significant public health problem.

Registration

PROSPERO (CRD42020215957).

Association of weight status and the risks of diabetes in adults: a systematic review and meta-analysis of prospective cohort studies

Obesity is a known risk factor for type 2 diabetes mellitus (T2DM); however, the associations between underweight and T2DM and between weight status and prediabetes have not been systematically reviewed. We aimed to estimate the relative risks (RRs) of prediabetes/T2DM in underweight/overweight/obesity relative to normal weight. PubMed, Embase, Web of Science, and Cochrane Library were searched from inception to December 8, 2021. Prospective cohort studies with a minimum 12-month follow-up period reporting the association between baseline body mass index (BMI) categories and risk of prediabetes/T2DM in adults were included. Study quality was assessed using the Newcastle-Ottawa Scale. The main analyses of T2DM risk were performed using the ethnic-specific (Asian/non-Asian) BMI classification and additional analyses of prediabetes/T2DM risk by including all eligible studies. Random-effects models with inverse variance weighting were used. Subgroup analyses and meta-regression were conducted to explore the potential effects of pre-specified modifiers. The study protocol was registered with PROSPERO (CRD42020215957). Eighty-four articles involving over 2.69 million participants from 20 countries were included. The pooled RR of prediabetes risk was 1.24 (95% CI: 1.19-1.28, I² = 9.7%, n = 5 studies) for overweight/obesity vs. normal weight. The pooled RRs of T2DM based on the ethnic-specific BMI categories were 0.93 (95% CI: 0.75-1.15, I² = 55.5%, n = 12) for underweight, 2.24 (95% CI: 1.95-2.56, I² = 92.0%, n = 47) for overweight, 4.56 (95% CI: 3.69-5.64, I² = 96%, n = 43) for obesity, and 22.97 (95% CI: 13.58-38.86, I² = 92.1%, n = 6) for severe obesity vs. normal weight. Subgroup analyses indicated that underweight is a protective factor against T2DM in non-Asians (RR = 0.68, 95% CI: 0.40-0.99, I² = 56.1%, n = 6). The magnitude of the RR of T2DM in overweight/obesity decreased with age and varied by region and the assessment methods for weight and T2DM. Overweight/obesity was associated with an increased prediabetes/T2DM risk. Further studies are required to confirm the association between underweight and prediabetes/T2DM, particularly in Asian populations.

A retrospective cohort study on the association between poor sleep quality in junior high school students and high hemoglobin A1c level in early adults with higher body mass index values

BACKGROUND

Few epidemiological studies have been performed to clarify the association between glucose metabolism disorders in early adults (20 years old) and physiological and environmental factors, including body mass index (BMI) in junior high school days. Therefore, we examined the association between hemoglobin A1c (HbA1c) level and body size (BMI) in early adulthood and lifestyles, including sleep habits and BMI in junior high school days in Shika town, a small town in Japan, by conducting a retrospective cohort study.

METHODS

We examined the HbA1c levels and body size (BMI) of 99 early adults who turned 20 years old between 2016 and 2020 and were residing in Shika town, Ishikawa Prefecture. We obtained the information on lifestyles and living environment factors, including BMI, from a questionnaire survey conducted among the subjects during their junior high school days (13-15 years old) from 2009 to 2013.

RESULTS

No correlations were observed between the HbA1c levels and the BMI values of the early adults. A two-way analysis of covariance (with the HbA1c levels and BMI values of the early adults as main factors) of the body size and lifestyle habits of the junior high school students revealed that "sleep quality in junior high school" was significantly poorer in the high HbA1c group than in the low HbA1c group in the early adults with high BMI values only. This result was also supported by the logistic regression analysis result.

CONCLUSIONS

The present results indicate that poor sleep quality in junior high school was associated with the high HbA1c levels of the early adults with higher BMI values, which suggests that good sleep quality in junior high school prevents the development of hyperglycemia. However, the present study did not find any relationship between early-adult BMI and HbA1c level.