doLoop.js

var magik = magikcraft.io;

magik.dixit('Initiating Game Loop');

if (gameloop) {
    magik.clearInterval(gameloop);
}

var gameloop = magik.setInterval(doLoop, 1000);
function doLoop() {
    const state = T1.state;
    let bgl = T1.state.bgl;
    const insulinOnBoard = T1.state.insulinOnBoard;
    const carbsOnBoard = T1.state.carbsOnBoard;

    const insulinAbsorptionRate = insulinOnBoard / 80 + 0.0025;

    if (insulinAbsorptionRate>0){
       // magik.dixit("AbsorptionRate: " + insulinAbsorptionRate);
    } 
    // do Insulin Absorption
    if (insulinOnBoard > 0) {
        const newInsulin = insulinOnBoard - insulinAbsorptionRate;
        if (newInsulin > 0) {
            T1.state.insulinOnBoard = newInsulin;
        } else {
            T1.state.insulinOnBoard = 0;
        }
         // do BGL Absorption
         if (T1.state.bgl > 0) {
             const bglAbsorbed = insulinAbsorptionRate * 0.8;
             const newBGL = T1.state.bgl - bglAbsorbed;
             if (newBGL > 0) {
                 T1.state.bgl = newBGL;
             } else {
                 magik.dixit("Aaaaaarggggh!");
                 T1.state.bgl = 0;
             }
         }
    }

    // Do BGL increase
    if (T1.state.insulinOnBoard == 0) {
        T1.state.bgl += 0.1;
    }
   // magik.dixit("Insulin: " + T1.state.insulinOnBoard);
    const insulin = T1.state.insulinOnBoard;
    T1.bars.insulin.setProgress(insulin);
 
    bgl = T1.state.bgl;
    T1.bars.bgl.setProgress(bgl);
    if (bgl > 0.2 && bgl < 0.4) {
        T1.bars.bgl.setColor(BossBarAPI.Color.GREEN);
    } else {
        T1.bars.bgl.setColor(BossBarAPI.Color.RED);
    }
}

t1.js

const magik = magikcraft.io;
const BossBarAPI = Java.type("org.inventivetalent.bossbar.BossBarAPI");
const TextComponent = Java.type("net.md_5.bungee.api.chat.TextComponent");

function t1() {
    T1 = { 
        state: 
        {
            insulinOnBoard: 0.2, 
            bgl: 0.4
        } 
    }

    var insulinBar = BossBarAPI.addBar(magik.getSender(), 
        new TextComponent("Insulin"), 
        BossBarAPI.Color.BLUE, 
        BossBarAPI.Style.NOTCHED_20, 
        T1.state.insulinOnBoard, // Progress (0.0 - 1.0)
    );

    var bglBar = BossBarAPI.addBar(magik.getSender(), 
        new TextComponent("BGL"), 
        BossBarAPI.Color.RED, 
        BossBarAPI.Style.NOTCHED_20, 
        T1.state.bgl // Progress (0.0 - 1.0)
    );

    T1.bars = {
            insulin: insulinBar,
            bgl: bglBar
        }
}