Table 4. Studies examining the association between breast milk insulin concentrations and maternal outcomes.
| Author, Year | Maternal n Number | Sample Type, Preparation and Analysis Protease inhibitor used | Time of day, fasted/fed | Timing of Collection (day/week/month) | Maternal BMI (kg/m2) | Breast milk Insulin (µIU/mL) | Statistical Analysis | |
| Shehadeh, 2003 | 90 | Milk type not reported. Skimmed. RIA. No protease inhibitor | Not disclosed | 3 days and 10 days post-partum | 23.7±5, time not reported | Day 3, 50.1±34.6* Median 41.0, Range 7-179 | Day 10 41.1±28.5 Median 34.0, Range 12-183 | Insulin concentrations were not significantly influenced by BMI on day 3 or day 10 post-partum. Spearman’s correlation |
| Ahuja, 2011 | 32 | Complete breast expression, whole milk analysed by ELISA. No protease inhibitor | 09:00-11:00 Not disclosed | 6 weeks post-partum | Pre-pregnancy Non obese 21.8±2.34, Range 18.5-24.7, Obese 32.2±3.82, Range 26.4-40.2 | Non-obese 4.5±7.6 | Overweight/obese 30.1±56.3 | There was a positive correlation between insulin concentration and maternal pre-pregnancy BMI (r = 0.57, p<0.001). Pearson’s correlation, non-logged values |
| Fields, 2012 | 19 | Complete breast expression. Skimmed. Immunoassay. No protease inhibitor | 8:00 -10:00am. Fasted 2h | 40 ± 4 days post-partum | Pre-pregnancy 26.6±6.6 | 23.6±18.01 | Insulin concentrations were not correlated with maternal BMI. Spearman’s correlation. | |
| Ley, 2012 | 170 | Foremilk. Skimmed. Electrochemilum-inescence immunoassay. No protease inhibitor | Not disclosed | 2 days post-partum, 3 months post-partum | Pre-pregnancy 24.4 ±2.9 | 2D Median (IQR), 24.5 (9.2/57.9), | 3M Median (IQR), 7.5 (4.9/12.5) | Higher pre-pregnancy BMI was associated with higher [insulin] in mature milk after adjustment for maternal age, ethnicity and time post-partum (β ± SEE: 0.053 ± 0.014; p = 0.0003) at 3 months, but not in the first week post-partum (β ± SEE: -0.002 ± 0.02; P = 0.91). General linear model |
ELISA: Enzyme-linked immunosorbent assay; post-partum: post-partum; IQR: Interquartile range; RIA: radioimmunoassay.
*Data are given as means and standard deviations unless stated otherwise.