Diabetes incidence and influencing factors in women with and without gestational diabetes mellitus: A 15 year population-based follow-up cohort study

Highlights

• The median time for developing diabetes in women with a history of GDM is 6.95 years.

• The total cumulative incidence rate of diagnosed diabetes at the median follow-up time of approximately 12 years was 9/1000 in women with GDM.

• BMI and family history of type 2 diabetes are major predisposing factors for future risk of diabetes in women with prior GDM.

Abstract

Aim

Very few extensive follow-up investigations evaluating patients with history of gestational diabetes mellitus (GDM) have been documented. We conducted this longitudinal study to estimate the incidence of diabetes and its predictors in women with and without GDM.

Method

A total of 2458 eligible women, aged 20–50 years (476 with GDM and 1982 without GDM) were selected from among participants of the Tehran Lipid and Glucose study, based on the World Health Organization definition for GDM screening. Pooled logistic regression was used to assess the association between time-dependent covariates and diabetes.

Results

The incidence rate of diagnosed diabetes was 9/1000 for women with GDM and 4/1000 for their counterparts, without GDM. Kaplan-Meier curve indicated a significantly shorter median time for developing diabetes in women with a history of GDM (6.95 years [IQ: 4.22–10.71]), compared to their healthy peers (8.45 years [IQ: 5.08–10.89]). BMI and previous family history of diabetes were found as major risk factors for future diabetes in women with GDM.

Conclusion

The results presented here lead to better identification and selection of at-risk women with prior GDM history.

Introduction

Type 2 diabetes mellitus (T2DM), as a chronic metabolic disease, is a major epidemiologic global concern which necessitates the early detection of risk factors and identification of at- risk populations [1]. Women with the history of gestational diabetes mellitus (GDM) are one of these challenging high-risk groups [2]. GDM, occurring in about 7% of all pregnancies and a well-established risk factor for T2DM [3], alters glucose tolerance and metabolism as well as insulin resistance [4]. In fact, when the elevated insulin secretion cannot meet the needs of pregnancy-induced insulin resistance status, GDM develops [5]. In a recent systematic review using 24 relevant papers, the prevalence of GDM among Iranian women was reported 3.41% (varying between 1.3% and 18.6%) [6].

Depending on the ethnicity of the study population, follow- up period and the diagnostic criteria used, approximately, up to 60% of women with GDM may progress to T2DM [7]. Data available suggest that GDM significantly increases both the adverse short-term pregnancy outcomes such as hypertensive disorders, macrosomia and caesarian section rate [8] as well as, the likelihood of long-term metabolic conditions in both mother and offspring [9]. Reports confirm the elevated risk of cardiovascular disease [10] and decreased pancreatic beta cell function [11] in women with previous GDM. Therefore, pregnancies affected by diabetes need to be followed and monitored regularly, in order to plan and intervene efficiently to prevent any adverse metabolic outcome.

We have previously shown that during a 9-year follow-up, T2DM was diagnosed in 27.3% of women with GDM and its cumulative incidence was about 3-fold higher than in normal women [12]. In the current study we aimed to investigate the incidence of T2DM in women with GDM compared to non-GDM women and to find out the influencing factors in diabetes progression, using data from a 15-year follow-up study of Tehran Lipid and Glucose Study (TLGS).